Hi All,

I need some helps to make Note and Attachment as mandatory before submit for approval.
currently I have created a checkbox field name: Attachment_c but don't know how to write a Apex code for Trigger. 
what I would like to do is:
if there is a file in attachment, then checkbox for attachment will be ticked, then you could click "submit for approval"
otherwise, you will receive a error msg: " Please attach claim form for approval"

current coding i have :

trigger TiggerName on attachment (after insert)
{
    Set<Id> attId = new Set<Id>();
    List<sObject> objList = new List<sObject>();
    for(Attachment at :Trigger.New){
        attId.add(at.ParentId);
    }
    if(attId.size() > 0){
        List<Retailer_Return_Request__c> recList = [select Id, Attachments__c from Retailer_Return_Request__c where id IN :attId];
        
        if(recList.size() > 0){
            for(Retailer_Return_Request__c a:recList){
                Retailer_Return_Request__c obj = new Retailer_Return_Request__c();
                obj.Attachments__c = true;
                objList.add(obj);
            }
        }
        
        if(objList.size()>0)
        {
            update objList;
        }                                                                   
    }
}
 with error msg:
Compile Error: Incorrect SObject type: Attachment should be Retailer_Return_Request__c at line -1 column -1

Thank you 

Will