VB 2005 winform app

I am trying to test a new method before dropping it's call into action on the form. In general I am determining if an edit will dupe particular columns that have no constraint.

This method is in my business layer, and the DAL which does the data pull needs the config settings in app.config.

I place the class designer in the WinForm project. I add the class and invoke it with the params I need. I get this error back?

'An unhandled win32 exception occured in dev.exe[4884]

I have placed the call in my code and it returns good/bad depending on inputs.

But how do you test in the class designer if your getting this type of an error?

TIA