BBM for iPhone won't download?

I recently 'got in the queue' for bbm to be downloaded onto my iPhone 4S and I got the email, but when I click to diwnloader it on the app, the screen just loads for a second and then goes back to the screen without doing anything. I've tried switching my phone off and on and re-entering my email address but it didn't work. Does anybody have any idea why this is happening or how to fix it?

You've to get in line…