Very simple target path problem

I have an image of a target on stage, that moves left and right.  In the center of the image is an invisible button, occupying the centre circle of the target.

The idea is you click the invisible button on the moving target and this starts another movie playing.

Seems to me the action script should reside in the button, and be something like this:

on(release){

targetPath(this.movie2);

play();

}