With DirectAdmin -- it is usually due to php handler not being listed in /etc/httpd/conf.d/modhostinglimits.conf
Check what your php handler is (usually in php.conf), and add it to AllowedHandlers in /etc/httpd/conf.d/modhostinglimits.conf
restart apache.
If that doesn\'t work, please contact our support at https://helpdesk.cloudlinux.com