You may not be accessing the actual day of the week.  To check and/or change the day of the week you must first press and hold the SET button.  While holding the SET button, press and hold the PROG/MAN button.  Release both buttons simultaneously.  The display will now show the current time of day.  Press and release the SET button once, and the display will now show the actual day of the week.  This is the day of the week that advances automatically day to day.  This day must be set to the correct day so that the program runs correctly.  Day 1=Monday down to 7=Sunday.