What causes a false signal to feed pellets?

Some Whitfield models, including the Optima 2, Optima 3, Profile 20, Profile 30 and Traditions, use a light sensor to detect a flame in the burn grate called the photoeye. This sensor in the pellet feed chute controls pellet feed and fan speed. If sunlight shines directly into the firebox it may reflect and trick the photoeye into behaving as if there is a fire in the burn grate. Block direct sunlight to prevent this false signal.