So I misunderstood, as usual
, what you described first.
Let me rephrase, just to be sure.
You have installed one Zentyal server as domain controller then deploy second Zentyal server on which LDAP master/slave is NOT enabled because you want this server to join "Samba domain" as secondary controller and when you set this you get this error, is that correct ?
Reading your post, I thought it was rather related to end-user trying to connect not using Windows Gina but rather LDAP based stuff
I'm confused. Sorry...