Oracle Message ORA-26028 - index string.string initially in unusable state

ERRORindex string.string initially in unusable state
CAUSEAn index is in IU state prior to the beginning of a direct * path load, it cannot be maintained by the loader.
ACTIONEither rebuild the index, re-create the index, or use either * SKIP_UNUSABLE_INDEXES or SKIP_INDEX_MAINTENANCE (Sql*Loader only).