LDAP integration question LTM

I've configured the remote authentication profile, it didn't work at all, when we did packet capture at the F5, we found that it was searching at the LDAP server with "UID" attribute, and that option is enabled by default, so we need to set that option to the username, and it worked fine. BUT this option is not acceptable at the customer side as we have +500 users, so we need to change that behavior to search with "SAMaccountname" instead, i tried to set filter and login attribute options but with luck, did anyone know a way to change that behavior??!