Functions

I’m reading Colin Moocks Actionscript for flash MX book and upon reading functions he instructs to create a symbol named ballSymbol, than put an instance on the stage (frame 1 maintimeline) and call it ball. Than on frame 1 on the main timeline put the following actionscript:


_global.mainTimeline = this;
 
function moveBall() {
mainTimeline.ball._x += 10;
mainTimeline.ball._y += 10;
};
moveBall();

The ball is supposed to move diagonally. But my problem is when I test the movie, nothing happens. No movement, nothing…

What am I missing?