Thanks for your suggestion.The users indeed login XOOPS with LDAP authentication method,and they did change their password using "Edit form" interface in XOOPS.But,when they finished changing their password,and login again,they still can't use new password,the correct one is old password.

Another scenario,while the user login learning system called MOODLE(Modular Objective Oriented Document Learning System) using the same LDAP server used in XOOPS,
they can change their password in MOODLE change password form.The password synchronized with LDAP server,LDAP server works fine.The problem appears in XOOPS.I am confused!Is it a bug??

I download XOOPS 2.0.16 (released 2006/11/17) from the official site,and installed it on CentOS platform,
every thing goes fine,and no error had founded!!I login the system with account called "root" sucessfully!
and set one of the authentication method called "Standardd LDAP Directory',and filled LDAP paramters in Administration Menu->Preference->Authentication Options,then I login XOOPS used account created on LDAP Directory sucessfuly.Every goes fine,and user can authenticate and login without baffle...
Once the user change their password under "Standardd LDAP Directory' authentication method, XOOPS tells user that profile updated and database updates sucessfully,but, when user login again,they can't use their new password,they still have to use the password before,this made user confuse,have anyone change your password under Standardd LDAP Directory' authentication method sucessfuly?this seems user LDAP Directory passwords not synchronize with changed one,is it a bug??

thanks for reading these messages