The above could indicate there is some kind of barrier between zones 3 and 4. The signal from the barrier is imposing on zone 4, causing smaller vehicles to be missed. Moving the zone boundary away from the barrier should help resolve this situation. Fine tune zone 4 by moving the zone boundary closet to the barrier further away from the barrier. A slight adjustment can make a large improvement.
Version 2.0 - Copyright © 2022, Image Sensing Systems, Inc. All rights reserved.