Dominic,
I just tried to go to your site, and it's in offline mode. If that's been the case while you're testing, then that is the cause of your problems. The Open Graph tags that JFBConnect adds to the page need to be visible to Facebook to scan. Since all your pages don't work (to Facebook or other public users), they can't see those tags. Additionally, if you just added the social features of Facebook, they want to see some public content to make sure that your page isn't spam, malware, porn, etc before they start publishing things in users walls. Once they see a little content, they'll be ok posting pages that may actually be for registered users only.
Hope that makes sense. Once you go live, it may take 1-3 days for Facebook to properly detect the Open Graph tags on your page. That's normal.
Let us know if you need anything else, and good luck!
Alex