Facebook Comments won't work

Hi, i’ve tried the official facebook plugin and SFC, and can get the like buttons to work, but not the facebook comments box to appear. I have tried multiple configurations, and changing themes. The theme i am currently using does use the new comment_form(), as do the others. Do you have any suggestions on how to get this to work? I had used this before on a different site about a year ago with no problems, but this time it has proved to be a pain. Your help would be appreciated.

http://wordpress.org/extend/plugins/simple-facebook-connect/