Domain mapping - 403 forbidden

Hi guys,

I got the following error when I try to access a site with a domain mapping:

- 403 Forbidden.

The domain mapping plugin is installed, the IP set in the Network Option (Domain mapping Configuration) and the custom domain entered for that portal.

I also modified my A record in my DNS to point to the IP in the network options.

Now, when I try to load the custom domain in the browser -> Error 403.

I use WP 3.0 + MU.

Thanks for your help.