1) decrease = the down-button
2) increase = up-button
3) stempel = the movieclip I want to stop on the Y-axis



var moveStempel = 0;

decrease.addEventListener(MouseEvent.MOUSE_DOWN, decreasePressed);
decrease.addEventListener(MouseEvent.MOUSE_UP, removeEnterFrame);

increase.addEventListener(MouseEvent.MOUSE_DOWN, increasePressed);
increase.addEventListener(MouseEvent.MOUSE_UP, removeEnterFrame);

function decreasePressed(e:MouseEvent):void
{
    moveStempel = 2;
    addEnterFrame();
}


function increasePressed(e:MouseEvent):void
{
    moveStempel = -2;
    addEnterFrame();
}




// ADD ENTER FRAME
function addEnterFrame():void
{
    this.addEventListener(Event.ENTER_FRAME, update);
}

function removeEnterFrame(e:MouseEvent):void
{
    this.removeEventListener(Event.ENTER_FRAME, update);
}

function update(e:Event):void
{
    if (stempel.y < 500)
    {
        stempel.y += moveStempel;
        trace("inside");
    }

    else if (stempel.y > 500)
    {
        stempel.stop();
        trace("outside");
    }

if ((stempel.y < 500 && moveStempel == 2) || (stempel.y > 300 && moveStempel == -2))
{
    stempel.y += moveStempel;
    trace("inside");
}
else
{
    stempel.stop();
    trace("outside");
}