The 9600 is a 5/2 day thermostat.  When the thermostat is programmed with four time and temperature settings (MORN, DAY, EVE, and NIGHT), it will run that program Monday through Friday (Days 1-5).  On Saturday and Sunday (Days 6 and 7), the thermostat automatically ignores the two middle settings and only runs the first and last settings (MORN and NIGHT).  In order for the program to run correctly you must tell the thermostat what the correct day of the week is by entering in a number of 1 through 7 at the appropriate place in the programming.