OHS: list only 2 metadata formats

I am trying to use OHS to harvest some data from OJS 2.4.8 which is installed on localhost (for testing purposes).

With http://localhost/ojs2/index.php/index/oai?verb=ListMetadataFormats, I have 5 formats listed (oai_dc, oai_marc, marcxml, nlm, rfc1807).

But, when I add archive in OHS, in Metadafa format I have only two listed: Dublin Core and MARC.

I want to harvest some data in NLM format, how to do that?

Thanks