play and stop movieclip with button

i want to play an mc from frame 1 to frame 20 - so far so good - here ist the script

rot_anim.stop();
function rot_animation (evt:MouseEvent) {
    rot_anim.gotoAndPlay(1);
    rot_anim.addEventListener(Event.ENTER_FRAME,fStop);
}
function fStop(evt:Event)
{
    if (rot_anim.currentFrame>19) { 
       rot_anim.stop();
       rot_anim.removeEventListener(Event.ENTER_FRAME,fStop);
    }
}
rot_anim.addEventListener(MouseEvent.CLICK, rot_animation);

now i would like to start to play the mc with a click on a button - but that does not work and i do not know what i am doing wrong. can anybody help me?

here is the script for the button calling the function

button1.addEventListener(MouseEvent.CLICK, fl_MouseClickHandler);
function fl_MouseClickHandler(event:MouseEvent):void
{
	rot_animation.play();
}