Why does my nintendo ds's "Games'n'Music" homebrew application hardly ever work when I put games on it?

Songs and music: fine, videos: ok, but games: temperamental. I download all sorts of apps and put them on my homebrew card but the games'n'music either freezes, doesn't work or doesn't recognize the game. Help! do i ned to format the disc or something? Or some kind off app format?? Helpppp!