Annual Appointment

I picked Donny up from school early today for his annual physical.  We were early to the appointment and I was feeling good.  I stepped up to sign in and the receptionist asked which doctor we were there to see.  When I told her, she gave me a very bizarre look and then informed me that the doctor wasn't in on Wednesdays.  I was slowly starting to get the picture.  I asked what day I was scheduled for because I wrote the appointment on the calendar.  She started typing and after a minute or two informed me that there wasn't an appointment.  You can imagine the joy Donny had when I told him we were leaving.  I pondered the situation the entire ride home.  Maybe I cancelled the appointment and just didn't remember to cross it off the calendar.  It just didn't make any sense, if the doctor's day of was Wednesday how could this be?  Well, I went through all my cards and found the card with the appointment.  I am getting old or maybe I'm in denial.  Do you see what I did?