Mouse Events Not Working for PNGs in MovieClips - Works for Vector Shapes

When I use the code below for a vector shape in a MovieClip, it works, but when I do the same exact thing where a png is used instead of a shape, nothing happens and the JavaScript breaks down. How can I do the same thing with pngs that I am able to do with vector shapes created in Animate? Thanks.

this.pngMe.on("pressmove", function(event) {
    var p = this.globalToLocal(stage.mouseX, stage.mouseY);
    this.pngMe.x = p.x;
    this.pngMe.y = p.y;	
}, this);