[Samba] can not join domain

[Judy Lin]

I have samba 2.2.8 is running as a PDC on RedHat Linux 7.3.
I can't seem to get my Windows-XP machine to join the domain.  Other
machines are already in the domain and work fine.  But when I tried to add
another machine to the domain, I'm running into problems.  I added a
machine account to the unix password file.  I also added a machine account
to smbpasswd.  Then, on the XP machine, I tried to join the domain and it
asks me to provide a username with privileges (which is root) in this
case, which also exists in /etc/passwd and smbpasswd.  Somehow it can't
find the PDC but it sill lets me join the domain.  When I go to log in, it
says it can't find a PDC.  Is there anything I'm missing here?

Judy