password changing problems

I've set up OpenLDAP 2.4.10 and have been using phpldapadmin for user management. The machines in our QA environment are set up to allow LDAP users to log in, and they are also able to change their password via the passwd command. However, they are only able to do this once; if they attempt it again, it bounces back with "LDAP Password incorrect: try again". They are able to log out and in regardless, but passwd will not accept their password in order to change it. If the user's password is reset in phpldapadmin, again they are able to change the password once, and no more. There is no password policy configured in slapd; should there be?

I have loglevel set to 296, but i'm not sure what to look for.

thanks rone