I wrote some code but its not working properly.....

<apex:page controller="OrderSummary" showHeader="false" action="{!QuerySalesOrders}">
    <apex:form >
          <apex:pageBlock >
            <apex:pageBlockSection >      
                            <apex:pageBlockSectionItem >
                                <apex:image id="Logo1" value=" {!URLFOR($Resource.CompanyLogo)}" />
                        </apex:pageBlockSectionItem>      
                        </apex:pageBlockSection>
            <apex:pageBlockButtons >
                <apex:commandButton value="Send Mail" action="{!SendEmai}" />    
                <apex:commandButton value="Cancel" action="{!CancelEmai}" />              
                 </apex:pageBlockButtons>
       
                                <apex:pageBlockSection title="Account Orders" columns="1"  id="pbs1" >
                                <c:AccountDataComponent />
                                </apex:pageBlockSection>
                            <apex:pageBlockSection >      
                            <apex:pageBlockSectionItem >
                                <apex:image id="Logo2" value="{!URLFOR($Resource.CompanyFooter)}"  />
                        </apex:pageBlockSectionItem>      
                        </apex:pageBlockSection>
            </apex:pageBlock>    
                                        
    </apex:form>
</apex:page>

global class OrderSummary{
    Id accId ;
    private final Account account;
    public OrderSummary(){
        account = [select Name, (SELECT Contact.Name, Contact.Email FROM Account.Contacts where Contact.Email != null)
                    from Account where id = :ApexPages.currentPage().getParameters().get('id')];
    }
    public List<Sales_Order__c> listSalesOrders {get;set;}
    
    /*
        The following method is used for displaying records in the view page
    */
    public pageReference QuerySalesOrders(){
        accId = Apexpages.currentPage().getParameters().get('id');
        System.debug('Account id :'+accId);
        /*List<Sales_Order__c> orders = new List<Sales_Order__c>();
        orders = [ select id,Sales_Order_Status__c from Sales_Order__c where Account_Name__c =: accId];
        String status = '';
        if(orders.Sales_Order_Status__c != null)
        {
        String[] order = orders.Sales_Order_Status__c.split(';');
        for(String s:order)
        {
        if(status == null)
        status = '\''+s+'\'';
        else
        status += '\''+s+'\'';
        }
        }*/
        listSalesOrders = new List<Sales_Order__c> ();
              
               
        listSalesOrders = [select Customer_PO_No__c, Sales_Order_Status__c, WIP_Status__c,
                           Despatch_Date__c, Revised_Despatch_Date__c, Revision_Details__c
                           from Sales_Order__c where Account_Name__c =: accId AND (Balance_Amount__c!=0 OR Balance_Quantity__c!=0) ];
        return null;
    }
    
    /*
        Get REcords for the component
    */
     global List<Sales_Order__c> getSalesOrders(){
        accId = Apexpages.currentPage().getParameters().get('id');
        System.debug('Account id :'+accId);
        listSalesOrders = new List<Sales_Order__c> ();
        
        listSalesOrders = [select Customer_PO_No__c, Sales_Order_Status__c, WIP_Status__c,
                           Despatch_Date__c, Revised_Despatch_Date__c, Revision_Details__c
                           from Sales_Order__c where Account_Name__c =: accId AND (Balance_Amount__c!=0 OR Balance_Quantity__c!=0) ];
        return listSalesOrders;
    }
    public Account getAccount() {
        return account;
    }
    
   /*
        The following method is used for sending Mails
   */
    public pageReference SendEmai(){
         Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage();
         EmailTemplate template = [select id from EmailTemplate where name ='OrderSummary'];
         String addresses;
            if (account.Contacts[0].Email != null)
            {
                addresses = account.Contacts[0].Email;
                // Loop through the whole list of contacts and their emails
                for (Integer i = 1; i < account.Contacts.size(); i++)
                {
                    if (account.Contacts[i].Email != null)
                    {
                        addresses += ':' + account.Contacts[i].Email;
                    }
                }
            }
                String[] toAddresses = addresses.split(':', 0);
                email.setToAddresses( toAddresses );
                email.setTemplateId(template.id);
                //email.setTargetObjectId('003O0000006bObU');
                try{
                     Messaging.SendEmailResult [] r =  Messaging.sendEmail(new Messaging.SingleEmailMessage[] {email});
                }catch(Exception e){
                    System.debug('Error while sending Mail :'+e.getMessage());
                }
               
        
        return new PageReference('/'+accId);
    }
    public pageReference CancelEmai(){
        return new PageReference('/'+accId);
    }

}