We've recently heard some reports from users about the Facebook Invite Friends feature no longer working on some Joomla sites. If your Facebook Invite Friends features has stopped working, please ensure you have upgraded to JFBConnect's newer Facebook Request system which was introducted in January this year with version 4.1.
Using Facebook to let your users invite their friends to your site can be an invaluable tool to grow your site quickly. Since it uses social sharing, it's proven that these methods of engagement have a higher click-through rate and are overall higher quality than many other promotional campaigns. Above all, using the Facebook invitation system is free!