Textfield holding playheadTime


I’ve created a textfield which I want to hold the time that is left of a flv being played. I also created a timer which will see to it that it gets updated.

Here is the code:
"import flash.utils.Timer;
import flash.events.TimerEvent;

var myTimer:Timer = new Timer(1000);
function updateCountdown(event:TimerEvent) {
cdText.text = myVideo.totalTime - myVideo.playheadTime;

However, when i try to compile i get this error message:
"1067: Implicit coercion of a value of type Number to an unrelated type String.