Remote Desktop Services on WS2K8 R2 and Windows Mobile 2003 Devices

Hi all,
I need to connect old devices (with Windows Mobile CE and Windows Mobile 2003) by RDP on a server with RDS role enabled.
The server is Windows Server 2008 R2.

Now, it works without problem on Windows Server 2003, but I have some problem to connect on Windows Server 2008 R2 for problems related to Authentication/Security.

Could you help me?

Thanks