Make sure the vibes setting on your case is turned on. Vibes cases have three settings instead of two, like most Duo cases have.
For the Lumee Vibes cases, here are the settings, in order:
1st click - Front Facing Lights
2nd click- Rear Facing Lights
3rd click- Vibes Music Detection Mode
4th Click- Standby
Here's a video demonstration of the case on the vibe feature: