[Dovecot] Dovecot and LDAP problems

[Spectron International, Inc.]

I'm having problems with dovecot and OpenLDAP. I installed both, and
configured both. /etc/dovecot-ldap.conf exists and I modified dovecot.conf
to have...

auth_userdb = ldap /etc/dovecot-ldap.conf
auth_passdb = ldap /etc/dovecot-ldap.conf

...but the log displays the following:

Jun 19 13:59:15 backup dovecot-auth: Unknown userdb type 'ldap'
Jun 19 13:59:15 backup dovecot: Auth process died too early - shutting down
Jun 19 13:59:15 backup dovecot: child 4187 (auth) returned error 89

the auth_userdb and auth_passdb seem to be ok, so what am I missing?

Faw