I found the failure by myself!! 
Look here for every who have the same issue:
From the kb, edit the following entry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\lanmanserver\parameters\size
Your choices for this registry key are 1,2 and 3.
1 = Minimize Memory Used
2 = Balance
3 = Maximize Throughput for File Sharing and Maximize Throughput for Network Applications
At my server there was it set to 1. I set it to 2 and it worked!
Thank you anyway for help!