Thanks Quanah/Mauricio/Chris for the reply.
In fact, that is the first thing I did, I get the following error when I start ldap service.
Checking configuration files for slapd: bdb_db_open: Cannot access database directory /var/vamail/ldap/mydomain.com (13) Backend_startup_one: bi_db_open failed! (-1) Slap_startup failed (test would succeed using the –u switch) [FAILED] Stale lock files may be present in /var/vmail/ldap/mydomain.com [WARNING]
Permission looks exactly the same. Any idea why this error?