Global Security Settings Manager doesn't allow localhost

I have a flashfile on my localhost that needs to connect to a remote server (for testing). I added the folder that contains the file to the Global Security Settings Manager, like this:

c:/inetpub/tankwars

This works fine, I can now play the file in a browser, with the url c:/inetpub/tankwars/game.html

But i want to use this url: http://localhost/game.html

But, even if I also add 'localhost' or 'http://localhost' to the Global Security Settings Manager, this doesn't work. Can anybody help me? Thank you.