If your LED doesn't light up, it's likely that you need to ‘reverse the polarity’ by flipping the LED. LED bulbs work like batteries with a positive and negative polarity. If the LED does not light up, simply remove the LED, flip direction and reinstall as shown below:
1. Remove the LED from the socket
2. Flip the LED
3. Insert LED back into the socket.
4. Check to ensure the LED lights up