Problem with Electricity Rates and TOU Periods

When I try to run a simulation after setting up energy charges, I get the error message "energy charge period not found for month m and period 3, Simulation utilityrate4 failed." What does that mean?
When you define energy or demand rates with time of use (TOU) rates, the number of periods in the rate table must be the same as the number of periods in the weekday and weekend schedules. For example, if the energy rate table only has rates for Period 1, and the schedules define periods for Periods 1, 2, 3, and 4, SAM cannot determine rates for Periods 2, 3, and 4, so displays the error message.