Hello well for the moment its not perfect yet sometimes ppl have some issues with reserving their nickname .
But here is what you should try to do 1 more time just to be sure :

1) Make sure you played on a server tracked by trackabse :
Check the server by ip or by name here : http://et.trackbase.net/index.php?mod=serverlist
2) if the server where you are usually playing isnt yet on the serverlist , please add it .
3) Try to check your nickname : http://et.trackbase.net/index.php?mod=search to make sure it has been created on trackase and check if no one reserved your name already , it could happen.

4) if all things above are correct for you then its just a little bug with symbols on your name like the < > but it should be fixed soon
waiting for your answer ! hope its gonne help you