domain mapping

I'm having a terrible time with this. I've tried it and it doesn't seem to want to work for me. Is there a updated installation file? I'm working with Hostgator and a cpanel... not sure if there's any trick there? I've got two sites set up (using subdomains)

and with domain mapping it just get the site sitting there... like its stuck in a loop. I've done a add-on domain with for now, but need to resolve this so I can start using the sites the way I need to. I had pro sites installed as well, but removed it until we get this fixed...

Also, one more question, to set up a apps email for the domain, i need to drop the google file in the root area of the subdomain? do I just put it in the root of the main domain? I can't seem to locate any specific files for the site other than the images folders which are all numbered.