I saw that the new 2.1 was out! I was excited!

But when I downloaded the demo and entered the registration code, I went to a multiplayer server and then there was a small note:
The registration code has been accepted.

But then... this message showed out:

The registration code was invalid, or it has been disabled!

What the heck?!?!?!?!!?!?

So please. Help me with this...