[Mailman-Users] IP's instead of FQDN

I'm new to mailman and have everything setup except for one problem. I've tried searching the archives but didn't find my resolution.

I have it installed (version 2.1.2) and created a list. It seems fine except that some of the links in the forms are not using my domain settings, rather that have an IP address in the URL like, 192.168.1.99. For example, when you try to subscribe the Subscribe button tries to post to the IP address rather than the domain.

I've tried setting the defaults for HOST and URL in defaults.py, but still can't get it fixed.

Can anyone tell me what I might be missing?

Thanks, James