Getting site sub domains to work with Pro Sites

I can’t get sub domains working on my Multisites install and with the Pro Sites plugin.

Here are my server/domain details:

DNS: I have my domain registered with GoDaddy, and the A record is pointed to my hosting server at MediaTemple. I’ve also set up a (*) wildcard A record that points to the same IP address.

At Media Temple, I have a Dedicated Virtual (3.5 Rage) hosting account with many vhosts for different websites. The domain I want to use for my Multisites install is NOT the primary domain on the MediaTemple DV hosting account.

I’ve set up MediaTemple and Plesk to map the domain to a vhost as I’ve done with many other websites in the past.

I’ve also done a few misc configurations within Plesk to help this along, but no luck.

When I set up a new site at a subdomain of my domain all subdomains simply point to my server’s IP address – they’re not even mapped to the primary domain in question. It doesn’t look like WP is picking up the subdomains and mapping them correctly.

Any help would be much appreciated.