What other Facebook extension are you using? Can you disable it?
The reason I ask, is because in your <head> section, there's the following line:
<script type="text/javascript" src="
connect.facebook.net/en_GB/all.js">
After this, there's a bunch of inline Javascript. I think that code is conflicting with JFBConnect. I'm not sure if it's necessary, but it doesn't look like it's doing anything. If you can disable it, it should hopefully fix the conflict and let JFBComments function properly.
Thanks