Milk Jug toss actively tracks the balls in the game using the optic on the conveyor to count the number of balls dispensed. If one of the score sensors in the game report that they have been activated it will deduct that ball from the total number of balls that are required to be dispensed. When the game registers an input for the score sensor it illuminates the white LED for the sensor and displays the score value on the display. If you did not see the white LED on the score sensor then you can divide the score displayed by the number of balls remaining will tell you which score sensor is being activated. You can also try rebooting the game to see if any errors are displayed during the power on sequence.