A lot of people don't understand what an 'advance' is. I got a $500 advance for my first novel, and then never earned another penny for it, because my cut of the royalties (which were meager, it wasn't a good contract) never exceeded $500. You only start 'earning royalties' after you 'pay back' that advance to your publisher, and some people don't know that it isn't like, payment for your work directly, but rather borrowing against future sales!