[ken_yap]

It may be simply that you need to remove that entry from the LDIF file with an editor since that object already exists.

It all depends on what you were trying to do, which isn't very clear. If your LDIF file was created with slapcat, it should be read in with slapadd. If it created with ldapsearch, it should be added with ldapadd. The difference is that slapcat/slapadd provides no schema checks, and the server must not be running. It's like a filesystem dump and restore. Whereas with slapadd, the server must be running, and any parents of an entry must exist already, and the entry must not be a duplicate of an existing entry (which is what you are seeing).