A dishwasher in a certain small restaurant can typically run six loads through the machine each hour. The restaurant manager offers dishwashers a double wage for each hour in which they run ten loads of dishes or more through the machine. Three months after this incentive program is begun, the restaurant$$s dishwashers have never earned this incentive, and employee productivity is the same as ever. Which of the following is probably the incentive program$$s most serious problem?