>I do not errors when running the form in a private datasession, but I just get a different result when I call a function from that form. Why???

What is the different result? Private Datasessions open up their tables fresh, so if you're relying on a record pointer being somewhere or an order being set, you'll have to replicate that in the Private DS.

ALso, there are a handful of SET commands that are scoped to the current datasession. That means, if SET DELETED is ON in the default datasession, it doesn't effect the state of SET DELETED in your private session, which could affect your results.