LDAP connection Status: Failure -null

I try to make a connection to our new OpenLDAP server with Oracle SQL Developer, but I am not successful.

The error message is: Status: Failure -null

When I connect to the old OID Server it works and the context of the LDAP Server is loaded.

What do I need that the context is read out with the SQL Developer?

On the LDAP Server I see just (with debug level 1):

591c2de7 slap_listener_activate(7):

591c2de7 >>> slap_listener(ldap:///)

591c2de7 connection_get(23): got connid=1001

591c2de7 connection_read(23): checking for input on id=1001

ber_get_next

ber_get_next: tag 0x30 len 12 contents:

591c2de7 op tag 0x60, time 1495018983

ber_get_next

591c2de7 conn=1001 op=0 do_bind

ber_scanf fmt ({imt) ber:

ber_scanf fmt (m}) ber:

591c2de7 >>> dnPrettyNormal: <>

591c2de7 <<< dnPrettyNormal: <>, <>

591c2de7 do_bind: version=3 dn="" method=128

591c2de7 send_ldap_result: conn=1001 op=0 p=3

591c2de7 send_ldap_response: msgid=1 tag=97 err=0

ber_flush2: 14 bytes to sd 23

591c2de7 do_bind: v3 anonymous bind

But no context can be chosen.