The character "@" has a special meaning, so needs to be doubled up to protect it.

The return value for InGroup is "1" (KiXtart TRUE), not "0" if the user is a member of the group.

This is more like what you want, I think:

Code:

SELECT
CASE InGroup("@@Cursus")
   $dep="cursist"
CASE InGroup("@@ICT")
   $dep="IT Rotterdam"
CASE InGroup("@@ARB")
   $dep="Employment & Benefit"
ENDSELECT