My iPhone isn't sending iMessages

Hi, I am having some trouble with my iPhone 4S (3G on Bell in Canada). I just got it 2 days ago and the data wasn't working when I first got it, I had that sorted out and it works fine now. Yesterday everything was working fine but today I went out and tried to send a message a few minutes after I had left the range of my home WiFi network and the progress bar for sending a message would go almost to the end then would stop, it eventually just sent as a text message (green instead of blue). Now I really want this sorted out because iMessage is the only thing that isn't working, the Safari web browser, AppStore and apps are all working fine on 3G. I have attatched a few images of my problem

The first error I got when I got home and tried to send an iMessage over WiFi

Went into the message settings and turned iMessage off and then on again; it said Waiting for activation... and then it said the iMessage sends messages to iPhones, iPad, iPod touch blah blah blah...

At this point it still gave me that first error message so I decided to enter my Apple ID by pressing the button "Use your Apple ID for iMessage"

This is what message I got when I signed in.

So, could anyone please help me I really need to get this error fixed! Thanks

And yes, I have tried re-booting, twice.