Extremely Weird iMessage Problem

I can receive iMessages from everyone

But when I send a message, it will always fail and sends as a text.

I used the Idiots guide to iMessage and iMessage worked fine, but after logging into iCloud, this problem started happening.

Now I have logged out of iCloud and redid the guide, and the problem still occurs.

Here is a pic of the problem: https://i.imgur.com/pzBfj18.png