Sorry i have never hear of it before.
Did you try using an ldap browser? That helped me to find the problem in my config.
I n my config this line
ou=people,dc=qnap,dc=local is in Bind DN Settings. Dunno if that helps. you can look in the ldap browser to see what it should be, in my case it was ou="mybusiness",dc=mydomain,dc=mydomainsuffix.