not sure how to fix it. I tried using an LED in the taillight and had the same problem. The light was lit fairly brightly, and it didn't change in brightness when I pressed the brake levers. So I turned the bulb around and it didn't change anything. I'm not sure how to get them to work in the taillight assembly.
I ended up just replacing them back with halogen bulbs
I'm using LED turn signals, and you have to replace the stock flasher to get those to work. But I have no idea how to get LED's to work in the taillight, like I said