WMI-Filter on Group Membership doesn't work

Hello everybody,

I have a Problem which maybe one of you can solve. I have a terminalserver which is in an AD-Group (not OU). The AD-Group is called "tsServer". The domain name is "test1" and I try to block the usage of the command prompt only on this server. I tried this through  a GPO with a WMI-Filter. The filter's query looks like this:
Select * from Win32_GroupUser Where GroupComponent="Win32_Group.Domain='test1',Name='tsServer'"

But it's not really working. Any suggestions how I can solve this?

Domaincontroller: Windows Server 2008 R2
Terminalserver: Windows Server 2012 R2