Error on updating custom tab

Hi

I have recently been redesigning one of our custom tabs that has always worked fine in the past but now needs some extra data. I have managed to get this part done, however now when you come up update an existing record, I am getting the following error:

SQLSTATE = 21000
Microsoft OLE DB Provider for SQL Server
Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.

No changes made to database.

UPDATE lt_corporate_bar SET lead_guest_lname = 'Ivanic' WHERE perf = 14152 AND num_guests = 1 AND lead_guest_fname = 'Suzanna' AND lead_guest_lname = ' Ivanic' AND status = '5' AND seat_dets IS NULL AND elig_reason = '414' AND notes = 'Hazard Chase - Mandeal''s agent' AND created_by = 'LOrr' AND create_dt = {ts '2009-10-29 11:56:57.440'} AND last_updated_by = 'CBatt' AND last_update_dt = {ts '2009-11-02 16:41:16.573'} AND id_key = 976462 AND customer_no = 20094779

Inserting new records and deleting records works fine. Any suggestions as to what I might have changed and how to fix it? I am using Infomaker (predicatably).

Thanks

Siobhan