When failing to scan a mumble server:

GAMETRACKER COULD NOT SCAN THE SERVER.
One of the following suggestions may help you:
Your server is currently offline.
GameTracker needs your server to be online before you can add it to our database. Please restart your server and make sure it's up before hitting ADD SERVER again.
You entered the wrong query port.
Please update your query port and hit scan again
Your server is firewalled.
Please turn off any firewall you have that may block scanning
Mumble scanning is currently ONLY AVAILABLE TO GAMESERVERS.COM servers.
Mumble scanning is currently ONLY AVAILABLE TO GAMESERVERS.COM servers, through the use of a custom plugin that is currently in beta. Wider support will be available in the future.

Fixed, thanks for pointing this out.