org registry?

[Bryan Irvine]

I've setup a new DNS server for my company and we're having all of our
customers that have a domain registered with us and we do DNS for
(about 15 or so) set the new server with their respective registrars. 
One snag has come up.  A company called ait domains gives error
messages like "$nameserver is not registered in the registry for
.org."

I can't get a hold of anyone at ait domains to figure what they are
talking about.  Anyone here know?  You don't have to register
somewhere in order  to host .org domains right?  I never have before,
and as far as I can tell the old nameserver is setup in any special
way.

Ideas on what this message means?

--Bryan