Basic Duplicate Help

programming flash
1

Im going for a mouse trail effect, but on the movement of a mc

onClipEvent(load) {
    speed=5;
    count=0;
}
onClipEvent(enterFrame) {
    _root.boxy._x=_root.box._x
    _root.boxy._y=_root.box._y
}
onClipEvent(enterFrame) {
    if(Key.isDown(Key.RIGHT)) {
        this._x += speed
    }
    if(Key.isDown(Key.LEFT)) {
        this._x -= speed
    }
    if(Key.isDown(Key.UP)) {
        this._y -= speed
    }
    if(Key.isDown(Key.DOWN)) {
        this._y += speed
}
duplicateMovieClip(_root.boxy, "boxy" + count, count)
count += 1
_root["boxy"+count]._alpha -= 2
_root["boxy"+count]._xscale -= 4
_root["boxy"+count]._yscale -= 4
}

The problem i have is in the [“boxy”+count]…it wont effect the new mcs. If i change count to a number though, it will effect that specific instance. Help?