Are you sure it isn't looking at the hostname that you are sending in the header?
If so, and since you're running on a Mac (?, I think you mentioned that in another thread), try:
edit /etc/hosts
put
1.2.3.4
www.domain.com domain.com
where 1.2.3.4 is the IP address of the new site, and domain.com is of course the domain. Shut down your browser, reopen it, then go to domain.com and see if it pulls up the 'new' site as the domain (it should). If it does, and you still get the error, then, you need to contact the Autogallery people.... but, I suspect they are looking at the hostname sent in the request rather than some hardcoded domain identifier somewhere.