Availability of Adaptive Follow-Up assignments is determined differently.Setting assignment dates determines when students can see, open, and work on a Mastering assignment in their Assignments list or calendar. This timing can be important.
Availability of Adaptive Follow-Up assignments is determined differently.
Each assignment has three dates that must all be set together. You can't set one date without setting the other two.
Available Until (must be later than the current date and no later than the course end date). This is the last date that students can open an assignment for review. 
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Aligning dates and points with your syllabus
Setting dates for assignments even before students enroll provides the advantage of displaying all assignments in the Gradebook, and enabling you to align dates and total points for Mastering assignments with your syllabus.
Making assignments available initially
Some students don't plan well unless they see an assignment on their Assignments list or calendar. Other students attempt to work on an assignment as soon as it becomes available, perhaps before they are adequately prepared. Options for addressing these concerns include:
As you enter due dates for unscheduled assignments, Mastering suggests an Available From date one week before the due date, but you can change this for any assignment.
Keeping assignments available until the course end date
Copied or newly created assignment?
When you copy an assignment, you have the option to copy the assignment dates (which you may need to edit). When you create a new assignment without copying, the dates are blank until you enter them. If an assignment has been copied to your course by a department coordinator, dates may be blank or set by the coordinator, and may need to be edited.
For information on setting or changing assignment dates, see the following topics: