If you are using Google Apps for Domains, you will need to submit a support ticket to have us make some changes to your account.

Here are the some (or all) of the things that need doing, depending on the extent you want to use it:

1. Set up your MX records (to receive email)
2. Set up your CNAME records (to use the calender, etc)
3. Remove a localdomains entry (if you are using a web-based email form on your site)