Setting up Active Directory service?

I am trying to set up the Active Directory service on our 7310. DNS points to our AD server (which also handles DNS service), NTP points to the AD server (which also supplies time services), 7310 image is 2011.04.24.1.0,1-1.8. I log onto the AD server and add the 7310 to the Computers list. I then go to the Active Directory page, click the "Join a Domain" button, fill in the domain name, Administrator, and the Administrator's password and hit the Apply button. It thinks about 30 seconds, and fails with a message about its failing because of clock skew between