I have created a Directory under Settings > User Management > Domain Management using Trail version of LivecycleES(turnkey) Admin UI.
In Edit Directory, I gave the Profile Name. In server settings tab, I gave the LDAP server information and the server test was successful. In Directory Users tab, I specified the Unique Identifier as "objectSid", since AD2003 is used, specified all the mandatory fields (Base DN,Login...)
When I test this, it returns
"The search criteria specified did not return any result"
But when I search the LDAP directory in the same hierarchy that was mentioned in the Base DN, the user is present in the LDAP.
Have you tried to populate the settings with the default Active Directory 2003 settings? That way you don't have to set them manually.
Usually when you get the "The search criteria specified did not return any result" it's because your unique identifier is not valid. I'm not sure if it's case sensitive but can you try "objectsid" instead.