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 or whitelist the gametracker scanning IP addresses:
208.167.241.190
208.167.241.185
208.167.241.186
208.167.241.183
208.167.241.189
108.61.78.147
108.61.78.148
108.61.78.149
108.61.78.150

Help me :'#

You had best tell them what server (IP / name) has the problem.
Your post, and profile provide no such information.

Reading those instructions should give you the most important tips.

Aside from that, you can check the link in the guide you did not include in the copy paste job:

http://www.gametracker.com/games/ts3/forum.php?thread=42258

For future questions, it's definitely helpful if you read the information right in front of you because it can save you a lot of time. Then, if you still have errors, be very specific so it's actually possible to assist.