Why does the system sometimes miss events?

The motion sensor can detect objects moving 25-30 ft (8-10 m) away. Detection sensitivity, mounting height, and mounting angle will influence the detection distance of your devices. We recommend that you adjust the detection sensitivity as needed.

The installation height should not exceed 3m, and the tilt angle should not exceed 15°. 

Objects coming directly toward the center of the camera may not always be detected. Where possible, position the camera so that movement crosses the field of view to some extent, which will assist in triggering the passive infrared motion detection.