[Samba] how to change password from win2k client

[Sohail Hasan]

I am using samba as a PDC for my WIN2K professional network. My 
configuration is as under:

[global]
        workgroup = ABC
        netbios name = COMPAQ
        server string = %h server (Samba %v)
        security = user
        encrypt passwords = Yes
        null passwords = Yes
        passwd program = /usr/bin/passwd %u
        passwd chat = *Enter\snew\sUNIX\spassword:* %n\n 
*Retype\snew\sUNIX\spassword:* %n\n .
        unix password sync = Yes
        syslog = 0
        log file = /var/log/samba/log.%m
        max log size = 1000
        add user script = /usr/sbin/useradd -d /dev/null -g 100 -s 
/bin/false -M %u
        logon script = \\%N\netlogon\logon
logon drive = H:
        domain logons = Yes
        os level = 99
        preferred master = True
        domain master = True
                                                                         
                                                                          
[netlogon]
        path = /export/smb/netlogon
        write list = JOHN

When i try to change a user password from my win2k client it says that 
"you do not have permission to change the password", what configuration 
parameter do i need to make that work.

Sincerely,

shasan