Originally Posted by till
The GD module is installed in the howto but maybe its not activated correctly. Check the file /etc/php4/apache2/php.ini , there must be a line extension=php_gd.dll that must be uncommented. When you changed the config file you must restart your apache webserver.
I think it's extension=php_gd.so
, not extension=php_gd.dll
. The latter one would be for Windows...