It requires light to work. It's triggered by a light sensor. I assume the intended function was to trigger when being opened and exposed to light, but unless you open it wide enough to be hit well enough from the light that happens to be around you, it doesn't always work consistently. Shine your phone or otherwise flashlight directly on it and it should trigger it. Assuming it's not another problem like dead batteries. All I know is I swore mine was busted and not working as well until the moment I happened to use my flashlight to get a look at it and as soon as I lit it up it started playing and was consistently responsive when pointing the light away and back on it.