RPC Server unavailable

RPC Server unavailable

Hello, first of all: I come from Germany, so my pronunciation is not the best :-).

Second: I've installed "Free Windows Admin Tool" (which is great by the way!). But I got just one problem... I've opend port 135, 445, 5000, 5001 and 5002 as told in the FAQ. But now, after I've added the client to my list, this is showing: The RPC-Server is unavailable. When I turn off the Windows Firewall it works perfectly. At work, I can't just turn off the Firewall... Is there any other solution, like I can let the Firewall on but still use the tool?

Thanks in advance!