samba - Dec 2004 - changing passowrd of a user by using winbind

Hi, 
 
I configured winbind to allow AD (Windows 2003 AD ) users to login to
Linux machines . The authentication is working fine , but i am phacing
one problem with winbind . Normally , after login into the machine, a
user can change his password through passwd command . When i am using
winbind for authentication and if i execute passwd  to change his/her
password, it's not working . I am getting an error user not known to the
underlying authentication module . 
 
Please, give me some help regarding this situation. 
 
 
 
Regards, 
shashi kanth