The platform is Fedora 14, but it should also work on Ubuntu and other Linux distributions as well.
If you follow LDAP tutorials which told you to edit /etc/openldap/slapd.conf but find your Linux distributor only set up /etc/openldap/slapd.d/ , then perhaps you have the same issue as I do.
In my case, the symptom is: after setting up LDAP server, ldapsearch works fine, but ldapadd and ldapmodify responds with "ldap_bind: Invalid credentials (49)."
The solution is adding olcRootPW directive in /etc/openldap/slapd.d/cn=config/olcDatabase={1}bdb.ldif , just like you have done in /etc/openldap/slapd.conf .
You can safely delete or rename slapd.conf , which is useless if slapd.d presents.
After restarting LDAP server, ldapadd and ldapmodify should work now.
