Flash Countdown Issue

So I have a background I want the text to stay within (see picture below) and the text doesn't keep the spacing.  Instead it reverts to 00:00:00:00 all next to one another.  Sorry about the coding, the formatted version is at the bottom.

this.onEnterFrame = function()

{

  var today:Date = new Date();

  var currentYear = today.getFullYear();

  var currentTime = today.getTime();

  var targetDate:Date = new Date(2016,0,31);

  var targetTime = targetDate.getTime();

  var timeLeft = targetTime - currentTime;

  var sec = Math.floor(timeLeft/1000);

  var min = Math.floor(sec/60);

  var hours = Math.floor(min/60);

  var days = Math.floor(hours/24);

  sec = String(sec % 60);

  if(sec.length < 2){

  sec = "0" + sec;

  }

  min = String(min % 60);

  if(min.length < 2){

  min = "0" + min;

  }

  hours = String(hours % 24);

  if(hours.length < 2){

  hours = "0" + hours;

  }

  days = String(days);

  if(timeLeft > 0 ){

  var counter:String = days + ":" + hours + ":" + min + ":" + sec;

  time_txt.text = counter;

  }else{

  trace("TIME'S UP");

        var newTime:String = "00:00:00:00";

        time_txt.text = newTime;

        delete (this.onEnterFrame);

  }

}