samba - May 2004 - troubles between a samba pdc server and its client

hye, people

I can' t join the domain from a client pc.
actually the pc is recognized as a menber of the domain 
but when I try to logon, even as root, it display the following
message:
"le systeme ne peut ouvrir de session sur ce domaine car 
le compte de l'ordinateur dans son domaine principal
est manquant ou le mot de passe est incorrect"
that it means the account of the computer is missing or the password is not
correct.
however, I'm sure of the right configuration of the smb.conf  file and
I've correctly created all the machines and users accounts on samba.

any ideas ?

charly