HLS VOD audio-only MP3 stream

I'm trying to setup an audio-only, on-demand HLS stream in FMS 3.5. I have no problems streaming the sample f4v files via HLS, nor do I have any issues streaming the mp3 files via RTMP to a Flash client. However, when I try to stream a sample mp3 via HLS (the mp3 file is located in the same directory as the sample f4v's), I get a 404 error.

Thoughts/suggestions? I can't find anything in the documentation about streaming audio via HLS on-demand.