To use Active-Directory as LDAP backend, you must change few things in the manager :
-  Use “ LDAP- ” as authentication and userDB backends, 
-  Configure authentication filter and mail filter  (“General Parameters » Authentication modules » LDAP parameters » Filters”)-  with: 
(&(sAMAccountName=$user)(objectClass=person))
(&(mail=$mail)(objectClass=person))
- 
-  Change the user attribute to store in Apache logs (“General Parameters » Logs » REMOTE_USER”): use the variable declared above 
-  Enable password modify extended operation if you want to change password in AD