If you want to authenticate to LDAP with system user/password then you dont need server identities element. Just follow section "SSL" from referenced article. (Not section SSL with Client Certificate).
Is your LDAP server configured to TLS/SSL on secured port. Btw. port 10389 you are connecting use to be unsecured port. Secured port use to be something like 636. Try to test SSL connection with openssl s_client.
What error do you see in log?
Thanks for fast response and proposal.
I found this setting and it increased the logging in a good way
Actually I think that our current problems are related to access problems (Firewall, account set-up or similar). So until I have sorted the out this will be pending.
Will be back.