[Dngrsone]

If using Calibre, then one can 'Open with' Calibre, but if the content is DRM'd, then you need a DRM plugin (I use the one provided through Apprentice Alf) and set it up before Calibre can read the book.

Also the DRM tool will only strip the DRM when Calibre imports the book initially, so if you have it in your library, you need to delete the protected book from Calibre first, then import it again after you have set up the plugin.

If you are trying to import the book directly from your Nook, then you might have an issue with your password or serial number.