smbpasswd failed for users

[patrice.ortega at solymatic.com]

I have installed samba.
Everything seems to be working fine except the smbpasswd executable file.
I can change a user's password as root with no problem but if a user tries to change his own password, it would give this error:
"machine 127.0.0.1 rejected the tconX on the IPC$ share. Error was : ERRSRV - ERRbadpw (Bad password - name/password pair in a Tree Connect or Session
 Setup are invalid.)."

I have these parameters specified in smb.conf :
   hosts allow = 10.10.  127.
   bind interfaces only = no
   encrypt passwords = yes
   smb passwd file = /etc/smbpasswd
   ...

I use SAMBA v2.0.6, PAM and SSH with a RedHat 5.2.

Please help  .. thanks for your time.