Mouse click sound placed on button down state only works first time

I reuse a button several times. Each instance I use the button, I have it named uniquely so I can access it through the code.  I have an mouse down event to play the mouse click sound in my library, an mp3. The first time it works fine. But never works again.

Here are my settings when editing the button:

Any ideas as to how to make the button sound click every time it is clicked upon?