Are you sure you didn't miss a day? If you miss a day, the door
will black out and the counter will not count that day.
If you missed out collecting the reward for the day - even if you
completed the task - the calendar will not count that door and
black it out the next day.
Oh, I just remembered that if you click on a door you opened, it
will say "you have already received this gift." If you click on one
you missed, it will say "this door has already been opened.
(RIP me, I was inactive for the first 4 days of the
calender)