Some weeks are cancelled due to weather or other unexpected reasons...so to help your attendance calculations etc not be affected by these empty dates in your home screen and season calendar do the following...
1. Go to Home - Season Calendar or Event - Calendar
2. Click on the view button for the date in question
3. Go to the very bottom of that screen (press the "end" button on your keyboard)
4. tick the box "Exclude from calculations" to exclude the attendance logic for this date...write a reminder why if you need
5. Press the Submit button