Web VPN RDP connection Issue

Hi,

I setup SSL Web based VPN and configured it properly. I am trying to access my RDP server through it. When I am trying ot connect my RDP server using QUICK menu or normal bookmark, I am getting a screen for enter user name and password but after that showing error "Connection Failed".

I am not sure but it is not a normal RDP session screen. It is from Fortigate it self. What I will put here. May I put here a RDP server username and password or fortigate user?

What is error?

Regards,

Deepak Kumar