Do you receive any message on the dash at all when you try to operate the roof? Error messages?
Sounds like you need to find another dealer. Check the fuses but other then that the quickest/easiest way to diagnose the roof will be with Star Diagnostic at a dealer. This is the diagnostic software the dealer uses to diagnose faults with the car. It can diagnose all the switches etc in the top without so much as removing a single panel.
If you are interested in diagnising the roof yourself this post will get you started:
more info regarding operation of the Vario Roof:
Finally, post #2 in this thread has a great .pdf for diagnosis and operation of the Vario roof: