Hello Ken, I'm sorry for the late answer.
To make it clear (I'm sorry I did'nt have enough time to do it in my fisrt question) and I am a real newbie in moodle so I'm really sorry if you find my questions obvious..
1) The moodle is installed in VM (ubuntu server) and I test it from my computer (windows) but I'm on VPN so I think that it means the moodle and the test are in the same server..
2) Apache Directory Studio is a plugin added to eclipse in order to test the connection with the LDAP using login and password and when I test it I get the entire tree of LDAP (I have to mention that the account I'm using is a "read only" account I don't know if it can create a problem or not because I see in an other discussion https://moodle.org/mod/forum/discuss.php?d=133486#p585234 that Admin user is recommanded)
3) While running php -m I found ldap
4) When I turned on debugging here is what I see:
Le module LDAP ne peut pas se connecter à aucun des serveurs Server: 'the host of my LDAP', Connection: 'Resource id #30', Bind result: ''
Error code: auth_ldap_noconnect_all
- line 488 of /lib/setuplib.php: moodle_exception thrown
- line 2161 of /auth/ldap/auth.php: call to print_error()
- line 215 of /auth/ldap/auth.php: call to auth_plugin_ldap->ldap_connect()
- line 4180 of /lib/moodlelib.php: call to auth_plugin_ldap->user_login()
- line 154 of /login/index.php: call to authenticate_user_login()
Thank you so much for your help