Fix forum tags isset error.
Fix forum tags isset error.

https://www.php-fusion.co.uk/forum/viewthread.php?thread_id=37696&pid=199144#post_199144

AlexL777/PHP-Fusion,Dahlgren/PHP-Fusion,helmuthm/PHP-Fusion,Jugolo/PHP-Fusion,AlexL777/PHP-Fusion,AlexL777/PHP-Fusion,Jugolo/PHP-Fusion,ALTUN69/PHP-Fusion,php-fusion/PHP-Fusion,Dahlgren/PHP-Fusion,slb4life/php-fusion,php-fusion/PHP-Fusion,slb4life/php-fusion,Dahlgren/PHP-Fusion,helmuthm/PHP-Fusion,ALTUN69/PHP-Fusion,php-fusion/PHP-Fusion,slb4life/php-fusion,helmuthm/PHP-Fusion,Jugolo/PHP-Fusion,ALTUN69/PHP-Fusion