If you've never been published before, you're an 'unknown quantity', so you're going to have difficulty selling your first novel.
('chiefly US') The 'big unknown' [=the important thing that everyone would like to know] is how investors will react.
A 'fear of the unknown' kept her from changing jobs.
(..) a merchant marine ship bound for Iceland left Bar Harbor. This was no ordinary trip. Once the ship got out to sea, for some unknown reason, the first mate went crazy and slit the throats of everybody on board the ship-- the captain, his wife, even his children (..)2009 The Black Waters of Echo's Pond