LDAP authentication problem

[Luc MAIGNAN]

Hi,

I use an OpenLDAP to authenticate linux users.
All seems to work fine.

But after several days, the users have to change their passwords 
(password expired). And even they can change it, the message is still 
the same (you have to change your password).
THe only way to permit them to login is that root change thier passwords 
directly via a smbldap-passwd.

So, how can I correct this ?
How can I prevent the password expiration ?

Thanks for any help

BR