authenticating users !

Hi

I have 2 backend db setup

{2}bdb -> suffix: ou=external,dc=xyz,dc=com {3)ldap -> uri ldap://msad.xyz.com, suffix: dc=xyz,dc=com

Say I have a user

dn: cn=alex samad,cn=users, dc=xyz,dc=com

I create an ldap alias record

dn: uid=alex.samad@xyz.com, ou=external,dc=xyz,dc=com objectclass: top, extensibleObject, alias aliasedObjectName: cn=alex samad,cn=users, dc=xyz,dc=com

I try and login with this DN "uid=alex.samad@xyz.com, ou=external,dc=xyz,dc=com" and it fails, when I logging with " cn=alex samad,cn=users, dc=xyz,dc=com " it works. So can I presume the authentication code doesn't follow ldap alias ?

Alex