Hi Experts,

I created a class to insert Account List Item Record for every Affiliation child record. 

Here is the code, and it's working in a single record, but when I executed the code manual in developer console I got an error message: 


Here is my code below: I think I need to use map but I'm just new and still confused on using map.
 

public with sharing class Eisai_InsertAccListItem_cls {
    
    List<Affiliation_vod__c> affChildRecsList;
    List<Account_List_vod__c> acctListInDb;
    List<Account_List_Item_vod__c> newAccListItem = new List<Account_List_Item_vod__c>();
    Set<Id>usersIdSet = new Set<Id>();
    
    public Eisai_InsertAccListItem_cls(){
        
        affChildRecsList = new List<Affiliation_vod__c>([SELECT Id, From_Account_vod__c, To_Account_Value__c, OwnerId
                                                         FROM Affiliation_vod__c 
                                                         WHERE Parent_vod__c = False
                                                         AND OwnerId IN :ActiveUsers()]);
        
            System.debug('Child Affiliation Records count ' + affChildRecsList.size()); 
        
        
        acctListInDb = new List<Account_List_vod__c>([Select Id, Name, OwnerId FROM Account_List_vod__c 
                                                      WHERE OwnerId IN :ActiveUsers()]);
        
            System.debug('Account List Records count ' + acctListInDb.size());
        
        
        
        for(Affiliation_vod__c affChild : affChildRecsList){
            for(Account_List_vod__c acctList : acctListInDb){
               if((acctList.Name.substring(3) == affChild.To_Account_Value__c)
                  && (affChild.OwnerId == acctList.OwnerId)){
                       Account_List_Item_vod__c AccListItem = new Account_List_Item_vod__c();
                       AccListItem.Account_List_vod__c = acctList.Id;
                       AccListItem.Account_vod__c = affChild.From_Account_vod__c;
                       newAccListItem.add(AccListItem);
                 }
             }
         }
   
        
        try{        
            insert newAccListItem ;
            System.debug('New Account List Item Records: ' + newAccListItem);
        }catch(DMLException e){
            System.debug('exeption catch ' + e.getMessage()); 
        }
        
        
    }//End of Constructor   
    
    public Set<Id> ActiveUsers(){
        
       List<User> usersIdList;
        
        usersIdList = new List<User>([SELECT Id
                                      FROM User
                                      WHERE (Profile_Name_vod__c LIKE '%Eisai_Epilepsy%' 
                                      OR Profile_Name_vod__c LIKE '%Eisai_PrimaryCare%') 
                                      AND IsActive = TRUE]); 
        
        for(User users : usersIdList){
            usersIdSet.add(users.Id);  
        }
        return usersIdSet;
    }
    
} //End of Class

Thanks for the help in advance