JW Player not working with s2member shortcode

We have just installed s2member plugin to replace another membership plugin and are trying to use s2member shortcodes to play an audio file hosted on Amazon S3/Cloudfront. We are testing using a page, but the player does not appear – nothing but a blank screen. We have tried changing the player_path in the shortcode to where we think the JW Player resides – but still no success.