Hi all,
Below error I am getting when I am trying to save my Trigger. please any one could  help me.
Error: Field is not writeable: METADATA_Source__c.SOURCE_CODE__c

My code is here:

trigger BrandTrigger on METADATA_Brand__c (After insert, after delete, after undelete,  before delete,after update, before insert, before update) {
  TACTHelper.setStatus();
  
   if(Trigger.isInsert && Trigger.isAfter){
    List<Metadata_Campaign__c> NewCampaign= new list<Metadata_Campaign__c>();
    List<METADATA_Source__c> NewSource= new list<METADATA_Source__c>();
    Map<string,string> Map1 = new Map<string,string>();
    List<Metadata_Program__c> Program= [select id,name from Metadata_Program__c where Program_ID__c='54'];
    List<METADATA_Therapy_Class__c> therapy=[select id,name from METADATA_Therapy_Class__c where Therapy_Class_ID__c='6'];
    String s1,s2,s3,s4;
    
    List<METADATA_Source__c> Sr=[SELECT SOURCE_CODE__c from METADATA_Source__c where SOURCE_CODE__c like 'CGI%' ORDER BY SOURCE_CODE__c DESC ];

     for(METADATA_Brand__c brand : Trigger.new){
      Metadata_Campaign__c camp= new Metadata_Campaign__c();
      METADATA_Source__c Sourc= new METADATA_Source__c();
        
        if(Program.size() > 0){
         camp.Program__c=Program[0].Id;
       }
        if(therapy.size() > 0){
         camp.Therapy_Class__c=therapy[0].Id;
       }
         camp.Name=brand.Name;
         camp.Campaign_Type__c='CIC';
         camp.Description__c=brand.Name +'CIC General Information';
         camp.Metadata_Status__c='A';
         camp.DISPLAY_FLAG__c='Y';
         camp.Branded__c='Yes';
         camp.USMM__c='No';
         camp.HCP__c='No' ;
         Newcampaign.add(camp);
         
         Integer k=1;
         for(METADATA_Source__c sorce: Sr){
         	Integer l=1;
         //	System.debug(sorce.);
         	S1= sorce.SOURCE_CODE__c;
         	S2=S1.Substring(5,S1.length());
         	Integer M= integer.valueof(S2);
         	Integer J=M+1;
         	
         if(Newcampaign.size() > 0){
         	Sourc.Campaign__c=Newcampaign[0].Id;
         }
         if(J.size()> 0){
         Sourc.SOURCE_CODE__c='CGIPH'+J;  // Showing ERROR Here

         Sourc.Name='Trigger'; // This has to be Delete. there is no Field called Source Name in Source Object
         Sourc.SOURCE_DESCRIPTION__c= brand.Name +'CIC General Information';
         Sourc.MEDIUM_TYPE__c='PH';
         Sourc.MEDIA_SOURCE_CODE__c='PHONE';
         Sourc.PURPOSE_CODE__c='CS';
         Sourc.ORIGIN__c='IRMA';
         Sourc.METADATA_STATUS__c='A'; // Probably this is default no need to mentioned here  
         NewSource.add(Sourc);
     }
     }
     }
      
  insert NewCampaign;
  insert NewSource;
   }
}

Trigger can able to insert record into Metadata_campaign__c and Unable to insert record into  METADATA_Source__c.
Please any one can help.. its Urgent
Advance Thanks...