The Contour i1 Air’s alarm will sound according to the last track you were listening to on your Apple device. If you are using iOS7 and  you close and force quit a third party App from which you want the alarm to sound,then this will result in the alarm not sounding.

To avoid this happening, play the track you want to awake to, and then just pause it. Or select a track from the Apple Music App and this will not occur.

Your alarm will now sound.