NT PDC to 2K DC

I just upgraded an NT PDC to 2k server, but for some reason, it will not see the domain. I do not want to use this PDC as a DC on the domain, I’d rather have it as a member server, but it is only seeing itself in a workgroup, and is not finding a domain when I try to connect it to one. has anyone ever run into this problem? Is there any fix for this? I need to get it on my doamin…
Thanks in advance for the help!