We will verify what is happening, maybe you can give to us a SSH access (send to support at grafxsoftware dot com).
Read our guide on
http://www.web-hosting-control-panel-addons.com/de scription.php/HOW-TO_setup_a_PLESK_Dedicated_Serve r/6/
Here we explain how to install mod_suphp. Power Toys just modify the vhost.conf