Help please! I need code for a button to stop a movieclip, when both are in a nested animation.

Question

I'm working on a project that has a button and a movieclip, which we want the button to stop, both nested in a movieclip on the main timeline.
The button instance = muteBtn
The clip to stop instance = backmusic
The movieclip they are nested in = ecard
There's also a preloader that works just fine on the main timeline.
I've seen a wide variety of ways to stop a streaming MP3 and they all look way too complicated for my current Flash knowledge level.  As far as I know, if the MP3 is in a movieclip, stopping that clip will also stop the MP3.  If that's just dead wrong and what I'm trying to do will never work, please just let me know so I can struggle in another direction.
What I'd prefer though would be the coding to make this button work.  I've tried a wide variety of ways to code something that seems like it should be so simple, and keep getting the error "Access of undefined property muteBtn".  I'm assuming this means it can't find the muteBtn in the nested layer.  How do I better define the muteBtn?  Do I then need to add something else that more clearly defines where the clip I want it to stop is since it is nested too?  PLEASE HELP ME!! Thank you in advance!
Some of what I've tried:
function endMusic(e:Event):void {
    ecard.backmusic.stop();
or
function endMusic(e:Event):void {
    backmusic.stop();
with...
muteBtn.addEventListener(MouseEvent.CLICK, endMusic);

Answer 1

When you target objects, you need to consider the path to the object based on where you are trying to target from.  So if your code is in the main timeline and your button is inside a movieclip, then you need to target the button via the movieclip...
   movieclipName.muteBtn.addEventListener(MouseEvent.CLICK, endMusic);
As far as stopping a moiveclip resulting in stopping a sound from playing, it is not likely to work.  To stop a sound you need to target the sound to stop it.