Problem creating new root virtual server

I am having problems adding a second server to my VM system. All virtuals will use the same IP since they are hosted on a cable connection with a single IP and the firewall NATing port 80 and 443 to them.

I am running slave DNS to my external DNS Server all zones in the external DNS point to the same IP.

When I add the new server I get this error: Failed to create virtual server : The domain ****.com is already hosted by your Apache webserver.

Is this because of the IP being the same for the domains? Do I need to make this a different type of VM?

Thanks