vShield Port Forwarding

vShield Edge 5.1

Public: 172.18.13.2

Private: 10.200.13.1

GW: 172.18.13.1

Traffic flow works fine. However, how do I portforward/dnat?

I wish to enable RDP, have configured my edge router to forward to vshield, which is fine, but I can't seem to figure the dnat out... See below:

I'm sure I'm doing this wrong. Trying to forward port 3389 from edge to a server on 10.200.13.10

Tanks.