If you say so. Anyway, like I said, blow into the cartridge NES style, put it in your system securely and snug, and boot it up again. I can't think of why it's not working.
You didn't happen to leave it in a pocket that recently went through the washing machine, did you? I know that tends to damage games.
edit: Before I leave for class, I also want to add in that you might should clean it. Take a q-tip and put a little all-purpose cleaner on it. Not too much, though. And then gently swab the inside of the cartridge and see if that helps. I know that works for NES games (gee, that keeps getting brought up a lot, doesn't it?) so I assume it will work for a handheld Nintendo game.