Please make sure you're using JFBConnect v4.0.3, which has numerous improvements for communication with Facebook. If you're already on 4.0.3, please post the URL of your site and Facebook page, so we can take a look.
Finally, you must post from the user account that you subscribed from. Support is only provided to active subscribers. To update your subscription, see:
www.sourcecoast.com/extensions
Thanks,
Alex