You might be asking for advice in the wrong place.
If you want to make money selling desktop apps, the advice you'll likely get from this crowd is "learn how to do it yourself." Otherwise, give your coder at least a 50 percent interest in all of the proceeds from this app.
Given what you tell us of his reaction, it sounds like you might be offering him an insulting percentage; think about it like: where would your idea to make a quick buck be without somebody who writes code?
Sometimes it's all about respect; other times it's about credit (being known for coming up with X); and still sometimes it's all about money, but most of the time it's a combination of the three. Find out what his combination is.