Epicor BPM LINQ in C# left outer join two tables with DefaultIfEmpty() is not working

Epicor ERP 10
13

I was able to use your example to make my query compile without errors. However, when I try to reference/set a field from one of selected query columns, I get the error message. See below for more details:
Error message:

Error Detail 
============
Description:  There is at least one compilation error.
Details:  
Error CS1061: 'System.Linq.IQueryable<AnonymousType#1>' does not contain a definition for 'OrderNum' and no extension method 'OrderNum' accepting a first argument of type 'System.Linq.IQueryable<AnonymousType#1>' could be found (are you missing a using directive or an assembly reference?) [GetTaskList.Post.Set_Quote_Number.cs(391,53)]
Program:  Epicor.Customization.dll
Method:  PrepareException
Line Number:  99
Column Number:  13
`

New left outer join:

var OrderHedDtlVar = (from o in Db.OrderHed.With(LockHint.NoLock)
join od in Db.OrderDtl.With(LockHint.NoLock) on o.OrderNum equals od.OrderNum into jointData_od
join cu in Db.Customer.With(LockHint.NoLock) on o.CustNum equals cu.CustNum into jointData_cu
from jointRecord_od in jointData_od.DefaultIfEmpty()
from jointRecord_cu in jointData_cu.DefaultIfEmpty()
where o.Company == TaskListVar.Company && o.HDCaseNum == CaseNumber && jointRecord_od.OrderLine==1

     //orderby l.TaskSeqNum ascending
//orderby l.TaskSeqNum descending

select new
{
o.OrderNum, o.RequestDate, jointRecord_od.PickListComment, jointRecord_cu.CreditHold

           });

 if (OrderHedDtlVar != null)
{
	TaskListVar["rsiOrderNum_c"] = OrderHedDtlVar.OrderNum; <-- error occurs at this line. 

}

`
old code without the left outer join:

    	
var OrderHedDtlVar = (from o in Db.OrderHed.With(LockHint.NoLock)
join od in Db.OrderDtl.With(LockHint.NoLock) on o.OrderNum equals od.OrderNum
join cu in Db.Customer.With(LockHint.NoLock) on o.CustNum equals cu.CustNum 
 where o.Company == TaskListVar.Company && o.HDCaseNum == CaseNumber &&  od.OrderLine==1 
           
         //orderby l.TaskSeqNum ascending
				 //orderby l.TaskSeqNum descending
               select new 
               {
                  o.OrderNum, o.RequestDate, od.PickListComment, cu.CreditHold

               }).FirstOrDefault();  

		
`