Sounds like you used the Admin Console to set this up. That means you are using Alfresco Enterprise Edition, and any support requests should typically go to Alfresco directly via the support portal (support.alfresco.com).
Did you really setup your LDAP server with the DNS name ldap.example.com? Otherwise this cannot work... On the other hand, you seem to have two users sucessfully synchronised.
What is weird, is that since I posted this, I tested logging into the admin console using an AD account and it was successful. So it would appear that the authentication mech is working, but the "test" feature is not.