Can't Connect With Remote Desktop Connection Having Problems, Need Help

Okay somehow I try connecting to my friends computer remotely he has a windows 7 and i already configured everything on his computer. But my computer is a Windows Vista Home Premium but somehow it wont let me connect it keeps saying in a dialog box with a error sound.

Saying this " Remote Desktop Disconnected"
"Try connecting again. If the problem continues, contact the owner of the remote computer or your network administrator.

But thing is its not my friends computer, its my computer I never could have use Remote Desktop Connection. I configured with my router EQ 660-R in NAT Rule, SUA Port 3389. Somehow in my firewall, it wont let me use the same port TCP 3389, it wont let me enter any number any its weird. Well I screen shot a picture so I will attach the picture so you can see what I mean. But I already made my friends computer a Static IP Configured router port forwarded on his and on his router everything worked fine but the problem is mine, that it won't let me port forward my router only if i use SUA Rule, in which i did with port 3389, and my Default Gateway Static IP. But on firewall it will not let me and I need help please. I Also added a exception to my Windows Firewall and also my Norton Internet Security 2013 Firewall, including the application, but somehow still it does not work. An how come my friends computer it works

Thanks I Would really appreciate if someone can help me with this.
I attached pictures by the way.

Heres the first one with the remote desktop connection error dialog box:

http://www.vistax64.com/attachments...help-remote_desktop_connection_dialog_box.jpg

An heres the second one which will not let me configure the port and this is what it says

http://www.vistax64.com/attachments...-having-problems-need-help-router_problem.jpg

Have you ever connected a remote machine across the internet using public IP addresses? The problem could be caused by many issues. Is your friends machine connected directly to the socket in the wall or is their a router behind it? If the later then it may not be possible to connect since multiple devices may be using that public IP address to connect to the internet (NAT - Network Address Translation).

Also may I ask what version of Windows 7 your friend has? Only Windows 7 Professional, Ultimate and Enterprise editions may be remotely connected to using Remote Desktop Connection.

Josh