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.
(..) It's . Look, I know we're coming at this backwards... But we can't commit to a firm launch date with this many unknowns. It's all right. Um... All models for launch will take days to reach Mars. They vary slightly in thrust duration... (..)2015 The Martian