Hello All,
I have written below code to parse values of excel sheet. It works fine if no of records is upto 4. But if i insert records beyond 4, i.e either 5 or 6 records, parse button didnt works. Below is the code.

public with sharing class InvoiceImportController {

	public InvoiceImportController() {
	}

	@RemoteAction
	public static Map<String, List<String>> getValidationData(string invoices, string invoiceDetails, string vendorBills, string vendorBillDetails) {

		Map<String, List<String>> outputMap = new Map<String, List<String>> ();

		// Parse the raw data
		List<invoiceStruct> invoiceList = parseInvoiceHeaders(invoices);
		List<invoiceDetailStruct> detailList = parseInvoiceDetails(invoiceDetails);
		List<vendorBillStruct> billList = parseVendorBills(vendorBills);
		List<vendorBillDetailStruct> billDetailList = parseVendorBillDetails(vendorBillDetails);

		// Capture the data points to validate
		Set<String> customerIds = new Set<String> ();
		Set<String> glAccountIds = new Set<String> ();
		Set<String> itemIds = new Set<String> ();
		Set<String> vendorIds = new Set<String> ();

		for (invoiceStruct inv : invoiceList) {
			customerIds.add(inv.record.Customer_ID__c);
			glAccountIds.add(inv.record.GL_Account_Id__c);
		}
		for (invoiceDetailStruct invDetail : detailList) {
			itemIds.add(invDetail.record.Item_Id__c);
		}
		for (vendorBillStruct vb : billList) {
			customerIds.add(vb.record.Customer__c);
			glAccountIds.add(vb.record.GL_Account_Id__c);
			vendorIds.add(vb.record.Vendor_Id__c);
		}
		for (vendorBillDetailStruct vbd : billDetailList) {
			itemIds.add(vbd.record.Item_Id__c);
		}

		Map<Id, Account> customerIdMap = new Map<Id, Account> ([select id from account where id in :customerIds]);
		Map<Id, GL_Account__c> glAccountIdMap = new Map<Id, GL_Account__c> ([select id from gl_account__c where id in :glAccountIds]);
		Map<Id, Netsuite_Item__c> itemIdMap = new Map<Id, Netsuite_Item__c> ([Select id from Netsuite_Item__c where id in :itemIds]);
		Map<Id, Account> vendorIdMap = new Map<Id, Account> ([Select id from Account where id in :vendorIds]);

		List<String> picklistInvoiceLocations = getPickListValuesIntoList('Invoice_Header__c', 'Location__c');
		List<String> picklistInvoiceStatuses = getPickListValuesIntoList('Invoice_Header__c', 'Invoicing_Status__c');
		List<String> picklistInvoiceRemitTos = getPickListValuesIntoList('Invoice_Header__c', 'Remit_to_Bank__c');
		List<String> picklistInvoiceDetailLocations = getPickListValuesIntoList('Invoice_Detail__c', 'Location__c');
		List<String> picklistVendorBillLocations = getPickListValuesIntoList('Vendor_Bill__c', 'Location__c');
		//List<String> picklistVendorBillTerms = getPickListValuesIntoList('Vendor_Bill__c', 'Terms__c');
		List<String> picklistVendorBillDetailLocations = getPickListValuesIntoList('Vendor_Bill_Detail__c', 'Location__c');

		outputMap.put('CustomerIds', new List<Id> (customerIdMap.keySet()));
		outputMap.put('GLAccountIds', new List<Id> (glAccountIdMap.keySet()));
		outputMap.put('ItemIds', new List<Id> (itemIdMap.keySet()));
		outputMap.put('VendorIds', new List<Id> (vendorIdMap.keySet()));
		outputMap.put('InvoiceLocations', picklistInvoiceLocations);
		outputMap.put('InvoiceStatuses', picklistInvoiceStatuses);
		outputMap.put('InvoiceRemitTos', picklistInvoiceRemitTos);
		outputMap.put('InvoiceDetailLocations', picklistInvoiceDetailLocations);
		outputMap.put('VendorBillLocations', picklistVendorBillLocations);
		//outputMap.put('VendorBillTerms', picklistVendorBillTerms);
		outputMap.put('VendorBillDetailLocations', picklistVendorBillDetailLocations);


		System.debug(outputMap);
		System.debug(glAccountIdMap);
		return outputMap;
	}

	public static List<String> getPickListValuesIntoList(String sobjectname, String fieldapiName) {
		List<String> pickListValuesList = new List<String> ();
		List<Schema.PicklistEntry> ple = Schema.getGlobalDescribe().get(sobjectname).getDescribe().fields.getMap().get(fieldApiName).getDescribe().getPicklistValues();
		for (Schema.PicklistEntry pickListVal : ple) {
			pickListValuesList.add(pickListVal.getLabel());
		}
		return pickListValuesList;
	}

	@RemoteAction
	public static Map<String, Object> loadData(string invoices, string invoiceDetails, string vendorBills, string vendorBillDetails) {
		System.debug('remoting loadData');
		Map<String, Object> retMap = new Map<String, Object> ();
		retMap.put('errors', new Map<String, Object> ());
		retMap.put('records', new Map<String, List<recordStruct>> ());
		List<recordStruct> retInvoices = new List<recordStruct> ();
		List<recordStruct> retInvoiceDetails = new List<recordStruct> ();
		List<recordStruct> retVendorBills = new List<recordStruct> ();
		List<recordStruct> retVendorBillDetails = new List<recordStruct> ();



		List<invoiceStruct> invoiceList;
		List<invoiceDetailStruct> detailList;
		List<vendorBillStruct> billList;
		List<vendorBillDetailStruct> billDetailList;
		try {
			invoiceList = parseInvoiceHeaders(invoices);
			detailList = parseInvoiceDetails(invoiceDetails);
			billList = parseVendorBills(vendorBills);
			billDetailList = parseVendorBillDetails(vendorBillDetails);
		} catch(Exception e) {
			((Map<String, Object>) retMap.get('errors')).put('Parse', e.getMessage());
			return retMap;
		}

		Set<String> accountIds = new Set<String> ();
		for (invoiceStruct inv : invoiceList) {
			accountIds.add(inv.record.Customer_ID__c);
		}

		Map<Id, Account> accountAddresses =
		new Map<Id, Account> ([select Id, Name,
		                      ShippingStreet, ShippingCity, ShippingState, ShippingPostalCode, ShippingCountry,
		                      BillingStreet, BillingCity, BillingState, BillingPostalCode, BillingCountry,
		                      Phone, Phone__c, Phone_2__c, Email__c, Fax
		                      from Account where id in :accountIds]);

		Savepoint sp = Database.setSavepoint();
		try {
			// Invoices
			List<Invoice_Header__c> newInvoices = new List<Invoice_Header__c> ();
			for (invoiceStruct inv : invoiceList) {
				Invoice_Header__c record = inv.record;
				Account acct = accountAddresses.get(record.Customer_ID__c);
				record.Billing_Addressee__c = acct.Name;
				record.Billing_Line_1__c = acct.BillingStreet;
				record.Billing_City__c = acct.BillingCity;
				record.Billing_State__c = acct.BillingState;
				record.Billing_Zip__c = acct.BillingPostalCode;
				record.Billing_Country__c = acct.BillingCountry;
				record.Shipping_Addressee__c = acct.Name;
				record.Shipping_Line_1__c = acct.ShippingStreet;
				record.Shipping_City__c = acct.ShippingCity;
				record.Shipping_State__c = acct.ShippingState;
				record.Shipping_Zip__c = acct.ShippingPostalCode;
				record.Shipping_Country__c = acct.ShippingCountry;
				record.Fax__c = acct.Fax;
				record.Billing_Phone__c = acct.Phone__c;
				record.Shipping_Phone__c = acct.Phone_2__c;
				record.Email__c = acct.Email__c;
				newInvoices.add(inv.record);
			}
			insert newInvoices;
			Map<String, Invoice_Header__c> invoiceMap = new Map<String, Invoice_Header__c> ();
			for (invoiceStruct inv : invoiceList) {
				invoiceMap.put(inv.tmpId, inv.record);
				recordStruct r = new recordStruct();
				r.tmpId = inv.tmpId;
				r.Id = inv.record.Id;
				retInvoices.add(r);
			}

			// Vendor Bills
			List<Vendor_Bill__c> newVendorBills = new List<Vendor_Bill__c> ();
			for (vendorBillStruct bill : billList) {
				newVendorBills.add(bill.record);
			}
			insert newVendorBills;
			Map<String, Vendor_Bill__c> vendorBillMap = new Map<String, Vendor_Bill__c> ();
            List<Vendor_Payment__c> vendorPayments = new List<Vendor_Payment__c>();
			for (vendorBillStruct bill : billList) {
				vendorBillMap.put(bill.tmpId, bill.record);
                if(bill.paymentRecord.Payment_Date__c != null){
                    bill.paymentRecord.Vendor_Bill_Id__c = bill.record.Id;    
                    vendorPayments.add(bill.paymentRecord);
                }
				recordStruct r = new recordStruct();
				r.tmpId = bill.tmpId;
				r.Id = bill.record.Id;
				retVendorBills.add(r);
			}
            if(vendorPayments.size() > 0)
                insert vendorPayments;
			List<Vendor_Bill_Detail__c> newVendorBillDetails = new List<Vendor_Bill_Detail__c> ();
			for (vendorBillDetailStruct billDetail : billDetailList) {
				billDetail.record.Vendor_Bill_Id__c = vendorBillMap.get(billDetail.tmpIdVendorBill).Id;
				billDetail.record.Customer_Id__c = vendorBillMap.get(billDetail.tmpIdVendorBill).Customer__c;
				newVendorBillDetails.add(billDetail.record);
			}
			insert newVendorBillDetails;
			for (vendorBillDetailStruct billDetail : billDetailList) {
				recordStruct r = new recordStruct();
				r.tmpId = billDetail.tmpId;
				r.Id = billDetail.record.Id;
				retVendorBillDetails.add(r);
			}

			List<Invoice_Detail__c> newInvoiceDetails = new List<Invoice_Detail__c> ();
			for (invoiceDetailStruct invDetail : detailList) {
				invDetail.record.Vendor_Bill_Id__c = vendorBillMap.get(invDetail.tmpIdVendorBill).Id;
				invDetail.record.Invoice_Header__c = invoiceMap.get(invDetail.tmpIdInvoice).Id;
				newInvoiceDetails.add(invDetail.record);
			}
			insert newInvoiceDetails;
			for (invoiceDetailStruct invDetail : detailList) {
				recordStruct r = new recordStruct();
				r.tmpId = invDetail.tmpId;
				r.Id = invDetail.record.Id;
				retInvoiceDetails.add(r);
			}
		} catch(Exception e) {
			database.rollback(sp);
			((Map<String, Object>) retMap.get('errors')).put('Insert: ', e.getMessage());
			return retMap;
		}

		((Map<String, Object>) retMap.get('records')).put('Invoices', retInvoices);
		((Map<String, Object>) retMap.get('records')).put('Invoice Details', retInvoiceDetails);
		((Map<String, Object>) retMap.get('records')).put('Vendor Bills', retVendorBills);
		((Map<String, Object>) retMap.get('records')).put('Vendor Bill Details', retVendorBillDetails);

		return retMap;
	}


	public static List<invoiceStruct> parseInvoiceHeaders(string invoices) {
		List<invoiceStruct> invoiceList = new List<invoiceStruct> ();
		List<Object> invoiceJSON = (List<Object>) JSON.deserializeUntyped(invoices);
		Id rt = Schema.SObjectType.Invoice_Header__c.RecordTypeInfosByName.get('Treasury').RecordTypeId;
		for (Object obj : invoiceJSON) {
			Invoice_Header__c row = new Invoice_Header__c();
			row.RecordTypeId = rt;
			Map<String, Object> raw = (Map<String, Object>) obj;
			string tmpId = (string) ((Map<String, Object>) raw.get('tmpId')).get('value');

			// Lookups
			row.Customer_ID__c = stringId(raw, 'Customer_ID__c');
			row.GL_Account_Id__c = stringId(raw, 'GL_Account_Id__c');

			row.Location__c = (string) ((Map<String, Object>) raw.get('Location__c')).get('value');
			row.Terms__c = (string) ((Map<String, Object>) raw.get('Terms__c')).get('value');
			row.Invoicing_Status__c = (string) ((Map<String, Object>) raw.get('Invoicing_Status__c')).get('value');
			row.Remit_to_Bank__c = (string) ((Map<String, Object>) raw.get('Remit_to_Bank__c')).get('value');

			row.Customer_PO__c = (string) ((Map<String, Object>) raw.get('Customer_PO__c')).get('value');
			row.Invoice_Period__c = (string) ((Map<String, Object>) raw.get('Invoice_Period__c')).get('value');
			row.Memo__c = (string) ((Map<String, Object>) raw.get('Memo__c')).get('value');

			//string dueDate = (string) ((Map<String, Object>) raw.get('Due_Date__c')).get('value');
			string coverageDate = (string) ((Map<String, Object>) raw.get('Coverage_Month__c')).get('value');
			string documentDate = (string) ((Map<String, Object>) raw.get('Document_Date__c')).get('value');

			//row.Due_Date__c = dueDate == '' ? null : Date.parse(dueDate);
			row.Coverage_Month__c = coverageDate == '' ? null : Date.parse(coverageDate);
			row.Document_Date__c = documentDate == '' ? null : Date.parse(documentDate);

			invoiceStruct struct = new invoiceStruct();
			struct.tmpId = tmpId;
			struct.record = row;
			invoiceList.add(struct);
		}
		return invoiceList;
	}

	public static List<invoiceDetailStruct> parseInvoiceDetails(string invoiceDetails) {
		List<invoiceDetailStruct> invoiceDetailList = new List<invoiceDetailStruct> ();

		List<Object> detailJSON = (List<Object>) JSON.deserializeUntyped(invoiceDetails);
		Id rt = Schema.SObjectType.Invoice_Detail__c.RecordTypeInfosByName.get('Treasury').RecordTypeId;
		for (Object obj : detailJSON) {
			Invoice_Detail__c row = new Invoice_Detail__c();
			row.RecordTypeId = rt;
			Map<String, Object> raw = (Map<String, Object>) obj;
			string tmpId = (string) ((Map<String, Object>) raw.get('tmpId')).get('value');
			string invoiceId = (string) ((Map<String, Object>) raw.get('Invoice_Header__c')).get('value');
			string vendorBillId = (string) ((Map<String, Object>) raw.get('Vendor_Bill_Id__c')).get('value');

			// Lookups
			row.Item_Id__c = stringId(raw, 'Item_Id__c');

			row.Location__c = (string) ((Map<String, Object>) raw.get('Location__c')).get('value');
			row.Item_Description__c = (string) ((Map<String, Object>) raw.get('Item_Description__c')).get('value');
			row.Policy_Number__c = (string) ((Map<String, Object>) raw.get('Policy_Number__c')).get('value');
			row.Memo__c = (string) ((Map<String, Object>) raw.get('Memo__c')).get('value');
			row.Ordinal__c = Decimal.valueOf((string) ((Map<String, Object>) raw.get('Ordinal__c')).get('value'));
			row.Unit_Price__c = Decimal.valueOf((string) ((Map<String, Object>) raw.get('Unit_Price__c')).get('value'));
			//row.Quantity__c = Decimal.valueOf((String) ((Map<String, Object>) raw.get('Quantity__c')).get('value'));
			//row.Vendor_Bill_Total__c = Decimal.valueOf((String) ((Map<String, Object>) raw.get('Vendor_Bill_Total__c')).get('value'));
			//row.Doc_Number__c = (string) ((Map<String, Object>) raw.get('Doc_Number__c')).get('value');
			row.Ignore_Vendor_Bill_Amount__c = boolean.valueOf((string) ((Map<String, Object>) raw.get('Ignore_Vendor_Bill_Amount__c')).get('value'));
			row.Is_Applied__c = boolean.valueOf((string) ((Map<String, Object>) raw.get('Is_Applied__c')).get('value'));

			invoiceDetailStruct struct = new invoiceDetailStruct();
			struct.tmpId = tmpId;
			struct.tmpIdInvoice = invoiceId;
			struct.tmpIdVendorBill = vendorBillId;
			struct.record = row;
			invoiceDetailList.add(struct);
		}

		return invoiceDetailList;
	}

	public static List<vendorBillStruct> parseVendorBills(string vendorBills) {
		List<vendorBillStruct> vendorBillList = new List<vendorBillStruct> ();
		List<Object> vendorBillJSON = (List<Object>) JSON.deserializeUntyped(vendorBills);
		//Id rt = Schema.SObjectType.Vendor_Bill__c.RecordTypeInfosByName.get('Treasury').RecordTypeId;

		for (Object obj : vendorBillJSON) {
			Vendor_Bill__c row = new Vendor_Bill__c();

			Map<String, Object> raw = (Map<String, Object>) obj;
			string tmpId = (string) ((Map<String, Object>) raw.get('tmpId')).get('value');
			// Lookups
			row.Customer__c = stringId(raw, 'Customer__c');
			row.GL_Account_Id__c = stringId(raw, 'GL_Account_Id__c');
			row.Vendor_Id__c = stringId(raw, 'Vendor_Id__c');

			row.Location__c = (string) ((Map<String, Object>) raw.get('Location__c')).get('value');
			//row.Terms__c = (string) ((Map<String, Object>) raw.get('Terms__c')).get('value');
			row.Memo__c = (string) ((Map<String, Object>) raw.get('Memo__c')).get('value');
			row.Vendor_Description__c = (string) ((Map<String, Object>) raw.get('Vendor_Description__c')).get('value');
			row.Ordinal__c = Decimal.valueOf((string) ((Map<String, Object>) raw.get('Ordinal__c')).get('value'));
			//row.Tran_Id__c = (string) ((Map<String, Object>) raw.get('Tran_Id__c')).get('value');
			row.Pay_By_ACH__c = Boolean.valueOf((string) ((Map<String, Object>) raw.get('Pay_By_ACH__c')).get('value'));

			//string dueDate = (string) ((Map<String, Object>) raw.get('Due_Date__c')).get('value');
			//string transDate = (string) ((Map<String, Object>) raw.get('Trans_Date__c')).get('value');
			string coverageFromDate = (string) ((Map<String, Object>) raw.get('Coverage_From__c')).get('value');
			string coverageToDate = (string) ((Map<String, Object>) raw.get('Coverage_To__c')).get('value');
			//row.Due_Date__c = dueDate == '' ? null : Date.parse(dueDate);
			//row.Trans_Date__c = transDate == '' ? null : Date.parse(transDate);
			row.Coverage_From__c = coverageFromDate == '' ? null : Date.parse(coverageFromDate);
			row.Coverage_To__c = coverageToDate == '' ? null : Date.parse(coverageToDate);
            string paymentDate = (string) ((Map<String, Object>) raw.get('Payment_Date__c')).get('value');
            
			vendorBillStruct struct = new vendorBillStruct();
			struct.tmpId = tmpId;
			struct.record = row;
            struct.paymentRecord =  new Vendor_Payment__c();
			struct.paymentRecord.Payment_Date__c = paymentDate == '' ? null : Date.parse(paymentDate);
			vendorBillList.add(struct);
		}
		return vendorBillList;
	}

	public static List<vendorBillDetailStruct> parseVendorBillDetails(string vendorBillDetails) {
		List<vendorBillDetailStruct> vendorBillDetailList = new List<vendorBillDetailStruct> ();
		List<Object> vendorBillDetailJSON = (List<Object>) JSON.deserializeUntyped(vendorBillDetails);
		for (Object obj : vendorBillDetailJSON) {
			Vendor_Bill_Detail__c row = new Vendor_Bill_Detail__c();
			Map<String, Object> raw = (Map<String, Object>) obj;
			string tmpId = (string) ((Map<String, Object>) raw.get('tmpId')).get('value');
			string vendorBillId = (string) ((Map<String, Object>) raw.get('Vendor_Bill_Id__c')).get('value');

			// Lookups
			row.Item_Id__c = stringId(raw, 'Item_Id__c');

			row.Location__c = (string) ((Map<String, Object>) raw.get('Location__c')).get('value');
			row.Is_Billable__c = Boolean.valueOf((string) ((Map<String, Object>) raw.get('Is_Billable__c')).get('value'));
			row.Description__c = (string) ((Map<String, Object>) raw.get('Description__c')).get('value');
			row.Policy_Number__c = (string) ((Map<String, Object>) raw.get('Policy_Number__c')).get('value');
			row.Cost_Center__c = (string) ((Map<String, Object>) raw.get('Cost_Center__c')).get('value');
			row.Invoice_Number__c = (string) ((Map<String, Object>) raw.get('Invoice_Number__c')).get('value');
			row.Rate__c = Decimal.valueOf((string) ((Map<String, Object>) raw.get('Rate__c')).get('value'));
			row.Quantity__c = Decimal.valueOf((string) ((Map<String, Object>) raw.get('Quantity__c')).get('value'));
			//if (!vendorBillDetailMap.keySet().contains(tmpId)) { vendorBillDetailMap.add(tmpId, new List<Vendor_Bill_Detail__c> ()); }
			//vendorBillDetailMap.get(vendorBillId).add(row);

			vendorBillDetailStruct struct = new vendorBillDetailStruct();
			struct.tmpId = tmpId;
			struct.tmpIdVendorBill = vendorBillId;
			struct.record = row;
			vendorBillDetailList.add(struct);

		}
		return vendorBillDetailList;
	}
	public static string stringId(Map<String, Object> raw, string fieldName) {
		string itemId = (string) ((Map<String, Object>) raw.get(fieldName)).get('value');
		if (itemId.length() == 15 || itemId.length() == 18) {
			return itemId;
		}
		return null;
	}

	class invoiceStruct {
		public Invoice_Header__c record;
		public string tmpId;
	}
	class invoiceDetailStruct {
		public Invoice_Detail__c record;
		public string tmpId;
		public string tmpIdInvoice;
		public string tmpIdVendorBill;
	}
	class vendorBillStruct {
		public Vendor_Bill__c record;
        public Vendor_Payment__c paymentRecord;
		public string tmpId;
	}
	class vendorBillDetailStruct {
		public Vendor_Bill_Detail__c record;
		public string tmpId;
		public string tmpIdVendorBill;
	}
	class recordStruct {
		public string tmpId;
		public Id Id;
	}
}