this.addEventListener(Event.ENTER_FRAME,EnterFrame );
function EnterFrame(event:Event):void {
    
    
    var today:Date = new Date () ;
    var currentYear = today.getFullYear();
    var currentTime = today.getTime();
    
    var targetDate:Date = new Date(currentYear,03,01);
    var    targetTime = targetDate.getTime()
    
    
    var timeLeft = currentTime - targetTime
    
    var sec = Math.floor(timeLeft/1000);
    var min = Math.floor(sec/60);
    var hrs = Math.floor(min/60);
    var days = Math.floor(hrs/24);
    sec = String(sec % 60);
    if (sec.length < 2) {
        sec = "0" + sec;
    }
    min = String(min % 60);
    if (min.length < 2) {
        min = "0" + min;
    }
    hrs = String(hrs % 24);
    if (hrs.length < 2) {
        hrs = "0" + hrs;
    }
    days = String(days);
    
    var counter:String = days + ":" + hrs + ":" + min + ":" + sec
    time_txt.text = counter;
}

var targetDate:Date = new Date(currentYear,03,01);