Cam does not pick up animal movement and human motion from a distance

We purchased the Stickup Cam Battery and installed outdoor mainly aimed to keep an eye on wild animals such as possums in the backyard, they have been feeding on flowers and digging lawns at night. The cam doesn't seem to pick up any animal movement, my cat ran through the zone multiple times during the day, nothing have been detected.  The other issue is this cam only picks up human movement if we walk pass the front of the cam, it doesn't pick up human movement if it is froma distance. the main reason we bought the cam is to pick up wild animal movements at night , also to watch out for trespass from the backdoor , this cam does none of that.  have we bought the wrong one?