Audio will not play on Keynote presentation

Hi there,

I have a presentation which requires a 30-second audio clip. I've imported the audio and the disc icon with a play button appears on the screen.

I have set the transition so that the picture comes in first and the audio should play after a 2-second delay. However, the audio doesn't play automatically in presentation mode.

When in editing mode, the audio plays if I click the play icon, but it doesn't play if I click the preview button in the inspector on the right-hand side of the screen.

I'm certain it is user error. Can anyone help me out with a solution?

Thanks!