I know your error,'cause i made it sometimes :P
If you put the "drawimage"command in the same "if keyhit" ecc ecc you are drawing the image if the button is pressed,so when the button isn't pressed the image is not drawn!
If you put the "drawimage"command in the same "if keyhit" ecc ecc you are drawing the image if the button is pressed,so when the button isn't pressed the image is not drawn!