Calendar view doesn't show the tasks I created

Calendar view doesn't show the tasks I created in Task Tree view or Task List view?

If you see the task in Task Tree view or Task List view but don't see it in the Calendar this may happen because of three things:

1. You forgot to set start and finish date.
2. You didn't assign the task to a Resource but Calendar view displays tasks of a certain Resource.
3. You assigned the task to a Resource but Calendar view displays the tasks of other resource or unassigned tasks.