I posted a couple of days back because WP 3.0 multiuser subdomains did not work with my host. Well, it turned out it couldn't work because the vhost files weren't right. Since my host has no intention of fixing this, I thought I'd give domain mapping a go with directories instead.
So I set up the directories and they work perfectly. Then I follow the tutorial at http://ottopress.com/2010/wordpress-3-0-multisite-domain-mapping-tutorial/ which directs me to a certain plugin. I follow the tutorial carefully. But I get the same error in the end as I got with subdomains: 503 Service Unavailable
Can this also be caused by the vhost-thingy or is this something else entirely? I did ping my domain the pointer is pointing to the correct IP address, the same as the domain does that actually work (the master domain).