Moving from local authentication to LDAP authent

Hi, I have already been configuring my users in Proctorria for many weeks, and when migrating to the V4 (ProjeQtor) i tried to add the LDAP authentication.
I've searched in the forum but i can't find informations that help me.
I tried to reset a user password before asking him to reconnect with his LDAP authentication....always rejected !

The users are already involved in different recorded projects, so i can't delete one just to verify from scratch the behavior afterwards.

Is there a way to specifically debug the LDAP phases between the ProjeQtor server and the LDAP server (nothing written in the log except 'Login error') ?

Obviously, all the requested LDAP fields have been completed with a "close application' and 'start application' .

Thanks.
Thierry