[Koha] koha with ldap

dear koha users, I have koha 2.2.5 working with ldap authentication on sles9, but seem to have a small issue: Every time an ldap user logs into koha, his/hers details are reset from the ldap server. So all updates through koha are lost. My ldap contains only limited info, and adding more details in koha is useless, this way. Is there a way to prevent this, or will I simple have to start adding ALL details in my corporate ldap server..? Regards, Mourik Jan