Facebook no longer supports custom parameters in sharer.php. The sharer will no longer accept custom parameters and facebook will pull the information that is being displayed in the preview the same way that it would appear on facebook as a post from the url OG meta tags. Use dialog/feeds instead of sharer.php

​https://stackoverflow.com/questions/20956229/has-facebook-sharer-php-changed-to-no-longer-accept-detailed-parameters