>>Now I get
>>

>>Msg 8156, Level 16, State 1, Procedure ap_GetReturnsForWarehouse, Line 23
>>The column 'Status' was specified multiple times for 'OrderedResultS'.
>>Msg 4104, Level 16, State 1, Procedure ap_GetReturnsForWarehouse, Line 23
>>The multi-part identifier "OrderedResultSet.RowNum" could not be bound.
>>Msg 4104, Level 16, State 1, Procedure ap_GetReturnsForWarehouse, Line 23
>>The multi-part identifier "p.PartNo" could not be bound.
>>Msg 4104, Level 16, State 1, Procedure ap_GetReturnsForWarehouse, Line 23
>>The multi-part identifier "r.SerialNo" could not be bound.
>>

>>
>>There are elements in that query I have never seen before. Very confusing.
>
>The inner part ( with row_number() ) was supposed to be a derived table. I'm guessing you didn't use
>
>select * from (derived table select with row_number()) OrderedRecordSet (alias I gave to the derived table) where rowNum = 1
>
>Can you post your exact query now to correct ?

I used exactly what you posted earlier:

select * from (SELECT	r.*, 
			p.PartNo, 
			p.Description,
			u.FullName,
			w.Caption AS Warehouse,
			r.Status, Row_Number() OVER (Partition by BatchID ORDER BY p.PartNo, r.SerialNo DESC) as RowNum
		FROM Returns r
		JOIN Parts p ON p.PartId = r.PartId
		JOIN Warehouses w ON w.WarehouseId = r.WarehouseId
		JOIN Users u ON u.UserId = r.UserId
		WHERE r.WarehouseId = @WarehouseId AND
			(@Status IS NULL or r.Status = @Status)) OrderedResultS 
            where OrderedResultSet.RowNum = 1
		ORDER BY BatchId, p.PartNo, r.SerialNo DESC