I followed this tutorial http://wiki.horde.org/FC4InstallationNotes?referrer=HowTo and I installed Horde on a FC4 when I try to setup the applications i get an error A fatal error has occurred You need the domxml or dom PHP extension to use the configuration tool. [line 25 of /var/www/html/horde/admin/setup/config.php] How can I fix this?