Stop Play action script 3 for mp3 on layer

Question

I this the wrong way to write a stop play for mp3 on layer.
I have buttons and sound within a movieClip.
Should I give outside movie clip instance name
Thanks
play_btn.addEventListener(MouseEvent.CLICK, playSound);
stop_btn.addEventListener(MouseEvent.CLICK, stopSound);
function playSound(e:MouseEvent):void {
    this.play();
function stopSound(e:MouseEvent):void {
    stop();

Answer 1

The code you show should work so you may have some implementation issues.
For the stop button error you should go into your publish settings and select the option to permit debugging so that the error includes a line number for what's causing the error.  A 1009 error indicates that some object your code is trying to target does not exist as far as the code sees it.... which can be due to a number of reasons, such as assigning code in a frame where the targeted object does not exist.
For the second error, it appears to be an issue loading (or possibly finding) the file.  Does the sound start playing on its own when you first run the code?
Usually an error of any kind will prevent a file from running properly, so it may just be an issue of fixing just one of them.
You normally don't have to wait for a sound file to completely load before executing a play command... that woiuld be counter-productive to the concept of streaming sound.  In theory, a play command following a load command will execute but the sound will not start until a sufficient buffer exists.