Where should you Never Set a Date on Discussions
The answer to this question is a simple one: Never set dates on Discussion Forums. If you are not sure what a discussion forum is, please review the tutorial on Understanding the Structure of Discussions within MyCourses. The dates set on discussion forums will override any dates you have set on individual discussion topics contained in the forum. This can cause real confusion for the students.
NOTE - Make sure you have already reviewed the tutorial on the Difference between Visibility vs. Locking Options on Discussion Topics.