Before you start implementing Facebook Connect feature in your website, kindly browse Facebook Connect Policy before proceeding. http://developers.facebook.com/policy/

Required PHP Extension

1. GD library (at least v1.8 with libjpeg)
2. Curl library (to retrieve information from external sites)

Required PHP Extension

1. fsockopen

Please also ensure that there is no Javascript or jQuery clash on your site because it will lead to error in executing Facebook Connect mechanism. We recommend you to use Firebug (a Firefox addon) to inspect such issues.