I used a Pass/Fail item for attendance, but when ICON calculated grades it did not use zeros for those students who hadn't passed. Why not?
This problem can occur when you have instructed ICON to exclude non-graded items from the grade calculation (to check, click 
Grade Settings and then click 
Calculation Options). Here's how to get around it: When grading a Pass/Fail item, click the 
Grade All icon at the top of the item Properties page and select Pass from the Grade dropdown menu; then manually enter 0 for students who did not complete the task satisfactorily. Otherwise, items for students you do not enter a grade for ("none" in the pass/fail menu) will be nongraded items, which will be excluded from ICON's calculations.
Important: When you use the Grade All function, your action affects all students in all sections of this course.