dn: dc=ltm,dc=uni-erlangen,dc=de
dn: o=ltm,dc=uni-erlangen,dc=de
These are clearly different root objects. You'll need to adjust the database root in your configuration to import your old database.
--Quanah -- Quanah Gibson-Mount Product Architect Symas Corporation Packaged, certified, and supported LDAP solutions powered by OpenLDAP: <http://www.symas.com>
