Wrong user when auto log in

Hi folks

I've got a problem with my Mac Mini OSX Server. It's running 10.8.2 just like all of the clients. Now if i click the server in Finder, my iMac connects with my Apple ID, or another wrong username. How can I force OSX connecting with the right username and password? Also, if I disconnect and then connect manually with the right username, everytime I close the Finder window, it connects with the wrong user again. What can I do?

Thanks in advance

malaclipse23