using slapindex on a running instance of openldap

Hi, I am using the gentoo build of openldap 2.4.23 with db-4.8 on a 64bit gentoo linux system.

I am trying to reindex a database after switching this database on readonly mode (by editing the bdb backend entry in th cn=config). The slapindex manpage read: Your slapd(8) should not be running (at least, not in read-write mode) when you do this to ensure consistency of the database.

But I get this error: sudo -u ldap slapindex -q member bdb_db_open: database "dc=univ-lille2,dc=fr": database already in use. backend_startup_one (type=bdb, suffix="dc=univ-lille2,dc=fr"): bi_db_open failed! (-1) slap_startup failed

Regards,