Adding Sound to Bouncing Ball

[Hurdarr]

Hi. So here's the deal. I have a as 3.0 .fla where a ball is just roaming around hitting walls and I would like to play a sound each time the ball hits one of the stage's wall, just like this.

I have this on my file:

var snd:Sound = new Sound(new URLRequest("TennisBall.wav"));

And on each if (when the ball hits one wall and changes it's course) I have:

snd.play();

Each time I run the game, I get no sound and the following error message:

Error #2044: Unhandled IOErrorEvent:. text=Error #2032: Stream Error.
at game_fla::MainTimeline/game_fla::frame1()
ArgumentError: Error #2068: Invalid sound.
at flash.media::Sound/play()
at game_fla::MainTimeline/moveBall()

What am I doing wrong here? All the code is placed on the first frame in the timeline.

Thanks.