Converting DGN to DWG in prostructures power product

Hi

I am exporting DGN's to DWG's but although the units in the DGN are set to millimeters, when the export is completed, the units in the DWG have changed to inches.

I have changed the unit tab in Export, DWG, Options, Basic, Units to millimeters but still when the export is done, the unit is inches