i have a soundTransform issue.

Question

i know i'm missing something stupid here. can someone give a hand? i'm trying to mute and make mcs invisible. i've done something wrong with the soundtransform bit. quite new on AS3.

var isPlayingMC:MovieClip =mc1;; 
var isPlayingMCcurrentFrame = 0;

var soundTr:SoundTransform = new SoundTransform();
soundTr.volume = 1;

btn1.addEventListener(MouseEvent.CLICK, playMC1); 
function playMC1(e:MouseEvent):void {

    isPlayingMCcurrentFrame = isPlayingMC.currentFrame; 
    isPlayingMC = mc1; 
    isPlayingMC.gotoAndPlay(isPlayingMCcurrentFrame);
    mc2.volume = 0;
    mc3.volume = 0;
    mc3.visible = false;
    mc2.visible = false;
    mc1.visible = true
}

btn2.addEventListener(MouseEvent.CLICK, playMC2); 
function playMC2(e:MouseEvent):void {

    isPlayingMCcurrentFrame = isPlayingMC.currentFrame; 
    isPlayingMC = mc2; 
    isPlayingMC.gotoAndPlay(isPlayingMCcurrentFrame);
    mc1.volume = 0;
    mc3.volume = 0;
    mc1.visible = false;
    mc3.visible = false;
    mc2.visible = true

} 
Btn3.addEventListener(MouseEvent.CLICK, playMC3); 
function playMC3(e:MouseEvent):void {
    isPlayingMCcurrentFrame = isPlayingMC.currentFrame; 
    isPlayingMC = mc3; 
    isPlayingMC.gotoAndPlay(isPlayingMCcurrentFrame);
    mc1.volume = 0;
    mc2.volume = 0;
    mc1.visible = false;
    mc2.visible = false;
    mc3.visible = true
    }

Answer 1

You need to actually apply your SoundTransform to the MovieClips, as they don't have a simple volume property:

var st1:SoundTransform = new SoundTransform();
st1.volume = 0;
mc1.soundTransform = st1;

Here's the relevant reference document.