Error 403

Okay, I have a dedicated IP (ie: 198.23.59.100 )for my site (ie: gridwp.com). I added seovoom.com as a A record pointing to this blog http://seovoom.gridwp.com

Now that the dns has resolved, I get a "error 403" Access forbidden!

What can I do to resolve this and get Domain Mapping working on my VPS?

Thanks