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.
(..) none other than Alfred Meinhardt. He makes guns, Big!... Guns Only days ago, A large share of his company was bought, by an unknown investor. Moriarty. The clues point in one direction, To avoid repeating last night's debacle, I was obliged to collect more suffient data, Hence my tardyness. (..)2011 Sherlock Holmes: A Game of Shadows