Check the "PIR Sensitivity" parameter setting. Set the sensor level to "High" for warm ambient conditions and "Low" for cold weather use. Try setting your camera in an area where there are no heat sources in the camera's field of view. Try to set the camera on a stable and immovable object, ie: a big tree. If the person/animal is moving fast, it may move out of the camera's field of view before taking the picture. Move the camera further back or redirect the camera.