Changing password from squirrelmail

hi,

I had configured openldap 2.3 in RHEL 5 operating system, and my squirrel mail is running in RHEL 4. I had integrated these two for address book synchronization. Its working fine .In my squirrelmail options i had change password option. I can able to chang the password by giving the old password and typing new password. SO that it will automatically changed in openldap database also for a particular user. But when am trying to change the password am getting error,

*"Your login account was not found in the LDAP database, cannot change password!"*