Student Submissions not showing up in grades?

[cadams6]

I have two students who tell me they have completed an assignment (a quiz) but I don't have the grade.  One sent me a copy of the confirmation screen showing she had submitted the assignment.  One says he completed it two days ago, so it shouldn't be a lag problem, I don't think.  

I have looked at Speed Grader and it says neither of these students have submitted any attempts.  I have looked at the student data analysis or whatever it's called (the Xcel document), and it shows no submissions since Thursday until today (both students say they did it Friday or Saturday).  

What could be the problem?

[lauren_sayer · Accepted solution]

Sometimes this occurs when students go over the time limit.  I would contact canvas help as they will see the submission from the backend and be able to provide information