Dellwyse USB problems on Server 2003

[scy]

I have dellwyse thin clients connecting to Windows Server 2003 via RDP.
Problem is that I can't save files to USB. I get the following error " Can't access \\tsc G you do not have sufficient priveleges contact your admin"

I have enables USB device in the Dellwyse setup.
Please help me resolve this problem.