External Entitiy with mixed GW2014/2012 and LDAP Auth


our GW System is in transition from GW 2012 to GW2014 - primary domain and three domains are already 2014, the remaining 16 domains are still 2012 SP2 - all running with LDAP authentication. According to the documentation one should now use the GW2014 Admin Webconsole, not ConsoleOne for administration (except for some domain level tasks).

Today I had to create a GW-Only user in a 2012 Post Office (formerly External Entity), so I created a new user in the admin console i the respective POA - worked - and I set a password... BUT when I try to log in with the new user, the GroupWise Client says: LDAP error. The POA log shows that the POA tries to authenticate the GroupWise user (only) against LDAP...
Doing the same in a GW2014 POA works as designed and old (migrated) external entities continue to work as designed...

How could I now create a External Entity in a GW 2012 post office?? Should I use ConsoleOne?

Anyways, we try to move up the schedule to migrate fully to GW2014.