[FMX04]: Problem with Events and loadMovie()

Hello,

probably another noob-mistake. I want to create a button
on-the-fly with actionscript. The following code works.
I create a movieclip, draw a black rectangle and add an
onPress listener to it.


    _root.createEmptyMovieClip( "arrow_up", this.getNextHighestDepth());
    arrow_up.beginFill(0x000000, 100);
        arrow_up.moveTo(0, 0);
        arrow_up.lineTo(70, 0);
        arrow_up.lineTo(70, 51);
        arrow_up.lineTo(0, 51);
        arrow_up.lineTo(0, 0);
    arrow_up.endFill();
    
    _root.arrow_up._x = 400;    
    _root.arrow_up._y = 283;
    
    _root.arrow_up.onPress = function() {
        trace ("pressed");
    }

What I do not understand is why the following code
does not work. I load a JPG instead of drawing some-
thing - but then the onPress event does not work
anymore.


    _root.createEmptyMovieClip( "arrow_up", this.getNextHighestDepth());    
    _root.arrow_up.loadMovie( "img/wdp_arrow_up.jpg" );
    
    _root.arrow_up._x = 400;    
    _root.arrow_up._y = 283;
    
    _root.arrow_up.onPress = function() {
        trace ("pressed");
    }

Anyone any ideas or explanations ???

Cheers,Mr E