=User!UserID parses servername instead of username

Hi Guys,

I have made a report that shows all activities from a user in the current week. No problems there. The only problem is: I want users to see their own activities and not from somebody elses. I use =User!UserID for that. In report builder results are fine. When I upload the rdl to crm 4, the =User!UserID seems to give back the servername and not the username...