>Thanks Mike,
>
>Now that I know the problem is not something in my own class I'm starting to think about solutions. One quick solution I have in mind for this form is, when the user choose a new parent, check if a child exist, if not, display a messages like 'this customer has no sales history' and reverse back to the previous customer displayed, no refresh of the form or grid in between.
>

That wouldn't work. The user would not be able to move past that customer.

>Anyway, I'll try your trick in a test form just to find out if it works, then I'll know better next time.