InfoPath Dev

Hi, We have a simple test form that we are trying to retrieve data into from a SQL Server (2008 R2) Stored Procedure. The procedure is very simple--it takes two parameters (from text boxes on the form) and filters a view based on those two parameters. Let me just say that we have other forms with stored procedures that are working just fine. The code is on an After Change event (we have other After Change events working fine) and works fine in PREVIEW mode in InfoPath but doesn't return anything when running in the Browser after we publish to the server. We are getting the following error: Execution thrown from business logic event listener: The database returns an error. One of more rows contain values violating non-null, unique or foreign-key constraints. We don't believe we have any rows containing values that violate any constraints so we're at a loss as to why we are getting this error. Any ideas? Thanks, Kathryn