onClipEvent and on (release) not working together?

programming flash
1

I’ve got an MC which acts like a button that comes onto the stage on frame 1. I want users to be able to press the MC so that a) it goes slides to x = 800, which I’ve managed to do… and b)goes to frame “start”.Any idea why it doesn’t move onto frame start after pressing the MC?


on (release) {
gotoAndPlay("start");
}

onClipEvent (load) {
        new_x = 170;
}
onClipEvent (enterFrame) {
        this._x -= (_x-new_x)*0.5;
}
onClipEvent (mouseDown) {
        new_x = 800;
}