99 318ti Taillight bulbs?? Never light?

[CYaunk]

When looking at the the car from the rear, on the left taillight, the bulb on the lower row and to the far right...then on the rightside taillight, the bulb on the lower row and to the far left....(closest to the license plate)..well they seem to not activate ANYTIME. I've done brakes, turn signals, normal taillights, etc..these two bulbs NEVER seem to come on and they are not burned out. Anyone know WHAT these are for or WHEN they should come on? Scratching my head on this one! - Chuck