Andrea,
Thanks for the credentials. I just got in to test. First, I checked all your settings, and everything looked right. Then, I went to the front-end directly (not in the FB Canvas) and registered through Facebook. I went to an article and created a comment. In the AUP activity log in the backend, the following line was added:
Friday, February 8, 2013 02:57 Facebook Comment Alex Sourcecoast alex.sourcecoast 10th Approved
So, that looks to me like it's working.
I was testing in Chrome. Can you try and see if you're still having the issue and if nothing shows up in the admin area?
Thanks,
Alex