>This is a SWAG, but remember that a function that doesn't return anything, actually returns .T. e.g.

LOCAL llTest
>llTest = .F.
>llTest = MyUDF()
>?llTest  && returns .T.
>
>FUNCTION MyUDF
>RETURN

>So, if you have an unhandled CASE, IF etc. it might lead to what you're seeing.

Thanks, we'll check for that.