fyi, there is problem in facebook at this momment on resgistering new Facebbok applications.
In short, when you register a facebook app and setup the namespace, then though you can save all the changes, when you try to access your application’s canvas URL
https://apps.facebook.com/your_new_namepsace
You will find that it cannot be resolved properly.
For details, see the bug report Navigating to a newly create app (with a canvas url) via apps.facebook.com/NAMESPACE fails to 4oh4.php