Hello, your issue is weird indeed. I would recommend sending K3lroy or woot a PM on the forums with a detailed explanation of the problem you're facing.
Ensure you're typing in the name correctly. When you type in the name make sure everything that needs to be capitalized should be capitalized. (Example: david_jhon might not work whilst David_Jhon will.)
When you signed up, you should have gotten an email that looked at least something like this
Ensure that the name you're typing matches the name in your email, letter for letter, capital for capital.
Also, try logging in on the launcher. To get this you can click anywhere on this entire sentence and it will re-direct you.
Please let me know if this helps, if not, update me with what else you've done to try and fix this.
@The other posts: I wont delete anything, but please be respectful that a new user is having an issue and does not need his thread spammed. Any other arguing following this post will be deleted. Thank you.