Few things can be happening. Make sure that you enable the movement sensor from the setting sections in the app (make sure you are connected to the table to enable it) also select the period of activity of it. (usually during the night hours).
Other probable situation can be that you are out of the sensing time range. Check in the app the beginning and end of activity hours you set. Finally make sure you are in the sensing range (max. distance: 6,5 feet)