By "not working" do you mean that the running light(s) aren't working? If so, when you changed the bulb 5 times did you make sure if the original and/or new bulbs were dual filimant? My only thought without seeing the car is that you put a single filimant bulb in place of a dual filimant. I've never pulled my taillight or changed any bulbs on my Crossfire so I can't confirm whether it's supposed to be dual filimant or not though.