setInterval and btn control?

programming flash
1

I want a button which starts the timer function when pressed and I can’t get it to do that!
This is the code I’ve written for the button:


on (press){
displayTime = 45; 
  	countDown = function(message){
  
  		displayTime--; 
  		if (displayTime == 0){
  
  			clearInterval(timer); 
  			gotoAndStop ("Time");
		}
  		}
}

and this for the frame above


timer = setInterval(countDown, 1000);

Any idea how I can make the button start the timer function?

Yossi