I have been reading through some of the solutions to other of these types of questions on balances but I can't seem to put them together to do what I need. So here goes. I have two tables, CASES and PAID. CASES holds hordes of information on a case including the original exposure amount in a field called, Exposure. CASES table also uses unique case identifier field called, Case#, to distinguish between cases. PAID holds payments made and the date that payment was made. PAID also uses a field called, CaseNumber, which uses the, Case#, field from the CASES table to tell which payment is for which case. I would like to sum the payments for each CaseNumber in the PAID table and subtract it from the Exposure in the CASES table and put it in a field in the CASES table called, Balance. I am using an update query to do this currently and have the following in the 'Update to' field: DSum("[PaymentAmount] ","[PAID]","[CaseNumber] =[CASE]![Case#]") When I run it I get the update warning box but it never seems to do anything to my CASES table.