UL1 needs to be calibrated in order to operate properly. Please watch this video to learn how to calibrate.
(1) Keep pushing down the inside handle of UL1.
(2) Use a paperclip to push the Reset hole around one second until you hear one "beep" from UL1.
(3) Calibration is done.
Note: Please have to calibrate once replace the batteries or restart UL1.