Hello shaun_9999,
there was a change in LDAP communication since the 6.3.1 release and it is not clear from the post on which version you are running on. Therefore we do not know what issues you might be facing. I would try to configure the connection via http://LEM_MANAGER_IP:8080/mvc/login . If it won't be working as well, open a ticket with our Support. They will know how to proceed. Please, do not forget to attach logs.
Thank you