Remote Desktop disconnected because of security error from Windows 8.1 Surface to Server 2008

Hello,

I am trying
to connect to a remote app on a 2008 server from a surface pro 3 with 8.1
through Netilla SSL VPN and I getting the following error message.

Remote Desktop Disconnected

Because of a security error, the client could not connect to the remote computer Verify that you are logged on to the network and then try connection again

if I am connected to the network and use the RDP file, it connects fine.

This
was previosluly working, but when I changed the terminal server to per user
license mode from trial mode this happen

This works fine from Windows 7 machines.<o:p></o:p>

Any ideas?

Thanks,

Derek