btw,
for security reasons, you should place your dataroot rather one level up (outside the httpdocs directory)
$CFG->dataroot = '/home/httpd/vhosts/heckmediamanagement.nl/moodledata';
Depending on your configuration in the php.ini (if open_basedir = ON) you will then need to change the open_basedir directive in the httpd.conf (of your vhost) ,so that php can access there.