Take a look at the pins inside of the bulb. You can see that there is 1 pin by itself, a gap, and then 2 pins together. When you connect the new HID headlight bulb to the adapter, the pin direction needs to match! Look closely at the adapter and you will see numbers denoting slots 1,2, and 4.

Make sure that the pins on the HID headlight bulb and the pin slots on the adapter directly match prior to connection. If you connect the HID headlight bulb and the adapter the wrong way, the connection will still go in, but the incorrect insert WILL cause the bulb to have issues such as not lighting up, flickering, or damage to your vehicle.

So before connecting the HID headlight bulb to the adapter, make sure that the pins from the HID headlight bulb match the corresponding open slots on the adapter.