Problems after changing IP on OD Master (OS X Server 10.4.8)

Hello:
Before describing my problem, I thought it might be useful to first point out that I’m a fledgling OS X Server administrator, and I’m learning all of this stuff as I go along.
I just set up a new OS X Server, which I configured to act as Open Directory master. Intially, everything seemed to be working fine. Since I was not using Kerberos, the server did not seem to require a fully qualified domain name.
At one point, I naively changed the IP address of the server and things went a little haywire as you can expect. At the time, I didn’t know about using changeip — all I did was reset the IP address in the network pane of the System Preferences, then I recreated the Share Point for user home directories after first deleting the old one. (All of the user accounts were brand new, so at least there were no user files to back up or migrate.) I also updated the configuration on the client machines.
Ever since then, I’ve not been able to connect to the Open Directory server. When I attempt to login with a username and password that I know to be accurate, what happens is that the login dialog window shakes as though the information were incorrect. However, if I attempt to access plain ol’ Apple file services witht he same username and password, I can log in, and I can even mount the user’s home directory.
When I found out about changeip, I ran it and then restarted the server. The command I used was this:
sudo changeip /LDAPv3/127.0.0.1 10.x.x.x 10.x.x.y
Because I hadn’t been relying upon a FQDN before, I left the last two parameters blank. I did receive an error that this might cause problems, but I was hoping this wouldn’t affect me. No such luck — I’m still experiencing the same issue.
I’m not sure of what my next step should be. Do I in fact need a domain name for my server so that I can run changeip again, and if so, do I actually have to register one with my domain registrar? Or do I set up DNS service (which is not currently running) on the server so that it points to its own internal IP address using some random domain name?
I currently have about 50 users who are successfully connecting to the server for basic file service, with all kinds of individual and groups permissions set on various directories and share points, but I’m attempting to move to a fully managed set up here. I’m just hoping that I don’t have to completely start from scratch and replicate all of that other work.
Thanks for your help,
David