SpeedGrader showing "needs grading" but there is no submission?

Community Contributor

I'm stumped by this. It is only happening with a few students, but what is going on? I  keep thinking I need to grade something only to find there is nothing there. Thanks for any help! 

Orange dot next to student name in SpeedGrader indicates a submission needs grading, and message in submission area says "This student does not have a submission for this assignment"