Trying to Access Remote Apps through Terminal Services Web Access

  We recently just set up a Terminal Services server with TS Web Access.
This server is a virtual server. In the scenario here, this server and the TS Gateway server are one in the same .

   I believe we have made all of the configurations prescribed by microsoft including TS CAP and TS RAP policies along with setting user permissions up, getting Terminal services to issue a cert, getting the clients to trust the cert,
and configuring the remote apps. From a client that is in network ( meaning the client exists on the same network as the terminal services server / gateway) everything works as expected.

Meaning:
1) the client goes to access the terminal services web page via a url.
2) They are prompted to authenticate
3) If authenticated, the web page with icons comes up (provided the Active X control has been installed)
4) The user clicks the icons that represent the remote apps.
5) The users are prompted again to authenticate(this time with the Gateway and remote ts server)
6) The apps come up.
7) Users are able to work with those apps.

Unfortunately when the user tries to access it from a computer  not on the network (out in "Internetland" in this case with a Windows 7 OS)  After step 4 above the user gets hit with this error.. "Your computer can't connect to the remote computer because the Remote Desktop Gateway server address is unreachable or incorrect. Type a valid Remote Desktop Gateway Server" address.

Obviously the user can connect if  if the web page and the gateway are the same machine. Why does it tell the user they can't reach the gateway ???

 Was wondering if anyone could provide any insight into this error. Any help would be greatly appreciated.

Jason