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?