Fade out music after playing for a minute AS3

import flash.media.SoundTransform;
import flash.media.SoundChannel;
import flash.media.Sound;
import fl.transitions.Tween;
import fl.transitions.easing.*;
import fl.transitions.TweenEvent;
var songReq:URLRequest = new URLRequest("name.mp3");
var song:Sound= new Sound();
song.load(songReq);
var thesong:SoundChannel = new SoundChannel();
var sTransform:SoundTransform = new SoundTransform();
startGameTimer();
function startGameTimer():void {
    trace("GAME TIMER STARTED");
    thesong = song.play();
    sTransform.volume = 0.5;
    thesong.soundTransform = sTransform;
    var gameTimer:Timer = new Timer(2000, 1);//1min
    gameTimer.addEventListener(TimerEvent.TIMER_COMPLETE, endGame);
    gameTimer.start();
}
function endGame(e:TimerEvent){
    trace("GAME TIMER ENDED");
    //thesong.stop();///want this to fade instead
   
    var tween:Tween = new Tween(sTransform, "volume", Regular.easeOut, sTransform.volume, 0, 1, true);
    tween.addEventListener(TweenEvent.MOTION_CHANGE, function():void
    {
        thesong.soundTransform = sTransform;
    });   
    var endTimer:Timer = new Timer(4000, 1);//fade out before transition
    endTimer.addEventListener(TimerEvent.TIMER_COMPLETE,changeFrames);
    endTimer.start();
}
function changeFrames(e:TimerEvent){
    gotoAndStop(5);
}