[Samba] Password expired

[Andrea Bencini]

I installed samba-3.0.28-0
I set "maximum password age".

pierluigim password has expired and so he would like to change it from XP 
prof client, but he receives this message:

"Lacking permission to change the password".

The global configuration of my smb.conf is:
-------------------
[global]
 name resolve order = wins bcast hosts
 ldap ssl = No
 passwd chat = *New*Password* %n\n 
*Re-enter*new*password*%n\n*Password*changed*
 show add printer wizard = no
 time server = yes
 passwd program = /usr/bin/passwd %u
 printing = cups
 workgroup = DMN-MAGIM
 server signing = Auto
 os level = 35
 printcap name = /etc/printcap
 add machine script = /usr/sbin/useradd -s /bin/false -d /var/lib/nobody'%u'
 delete user script = /usr/sbin/userdel -r '%u'
 max log size = 100
 restrict anonymous = no
 smb ports = 139
 add group script = /usr/sbin/groupadd '%g'
 delete group script = /usr/sbin/groupdel '%g'
 add user to group script = /usr/sbin/usermod -G '%g' '%u'
 logon drive = R:
 username map = /etc/samba/smbusers
 domain master = yes
 encrypt passwords = yes
 passdb backend = tdbsam
 wins support = Yes
 max protocol = NT
 path = /data
 unix password sync = yes
 acl compatibility = winnt
 logon path =
 add user script = /usr/sbin/useradd -m '%u'
 set primary group script = /usr/sbin/groupadd '%g'
 syslog = 0
 preferred master = yes
 domain logons = yes
 pam password change = yes
-----------------------

and in my log.smb file I have:
----------------------
[2007/12/20 19:02:10, 0] auth/pampass.c:smb_pam_chauthtok(691)
  PAM: UNKNOWN PAM ERROR (19) for User: pierluigim
[2007/12/20 19:02:10, 0] auth/pampass.c:smb_pam_passchange(847)
  smb_pam_passchange: PAM: Password Change Failed for user pierluigim!
[2007/12/20 19:02:10, 0] auth/pampass.c:smb_pam_chauthtok(691)
  PAM: UNKNOWN PAM ERROR (19) for User: pierluigim
[2007/12/20 19:02:10, 0] auth/pampass.c:smb_pam_passchange(847)
  smb_pam_passchange: PAM: Password Change Failed for user pierluigim!
[2007/12/20 19:02:10, 0] auth/pampass.c:smb_pam_chauthtok(691)
  PAM: UNKNOWN PAM ERROR (19) for User: pierluigim
[2007/12/20 19:02:10, 0] auth/pampass.c:smb_pam_passchange(847)
  smb_pam_passchange: PAM: Password Change Failed for user pierluigim!
[2007/12/20 19:02:10, 0] auth/pampass.c:smb_pam_chauthtok(691)
  PAM: UNKNOWN PAM ERROR (19) for User: pierluigim
[2007/12/20 19:02:10, 0] auth/pampass.c:smb_pam_passchange(847)
  smb_pam_passchange: PAM: Password Change Failed for user pierluigim!
------------------------------
Can you help me?
Thanks
Andrea