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.
(..) Aleksei Sytsevich. He is most eager to join us. Russian ganster Aleksei Sytsevich was broken out of a classified penetentiary known simply as 'The Vault' by an unknown team of men. It's yet another example of increased criminal activity since the disappearance of Spider-Man months months ago. (..)2014 The Amazing Spider-Man 2