IDE :: SWF Won't Play Properly?

I'm working on redoing some very old HTML/Javascript effects on a client's website using Flash for better browser compatibility. On one of the pages, there is a SWF on/off audio button that when the page loads immediately starts playing audio (I didn't make this myself, it's already on the site). When you click the button, the sound goes off, and on again when you click a second time.

I downloaded the SWF and whenever I open it up in Flash player it functions fine, as it should. However, when I try to load it into an empty movie clip on the FLA I'm working on, it doesn't work. You have to click the button to get the audio to play, and then it won't turn off again. It's very odd.I'm using CS4 and AS2. Here's the code I'm using to load the SWF. "Sound" is the empty movie clip. It loads, but just doesn't function properly and I can't seem to fix it. I don't understand why the SWF isn't functioning as it does when you open it in Flash player.

Code:
loadMovie("cs_clip.swf", "sound");