Microsoft VAMT 2.0 Problem

Hello,
I’ve decided to use MS VAMT 2.0 to organize the Windows Activations in our corporate network, but I found a problem which I can’t decide several days.
I have a windows 2008R2 server with VAMT 2.0 tool install on it. My workstations are with installed Windows 7 OS and with enabled WMI service. I’ve allow all WMI traffic in the workstation’s firewalls.
The problem is that when I add a computer with its name in the VAMT tool it can’t communicate with WMI on the workstation. When I add the computer with its IP address everything is working.
I’ve the proper resolving of the computer names from this server.

Do you have any suggestions for resolving this problem?