LDAP auth backend assumes things about how first and last names can be gathered.
Review Request #399 — Created May 27, 2008 and submitted
first_name and last_name are gathered (currently) by space-splitting the 'cn' field. This is correct unless you don't have spaces in your 'cn' field at which point user creation fails. I have switched to using displayName, but this is not a permanent fix. I might recommend something similar to LDAP_UID_MASK, but it is not likely as simple.
I tested this on my server by logging in with an unregistered user using the LDAP backend. The user creation was successful.