If you chose not to set your quiz to be Automatically Graded upon completion you will need to mark the quiz attempts so that the results can be exported to the grade book (if applicable) and to make the quiz results available to the student.
An easy way to determine if a quiz attempt has not been graded is to look at the Published column on the Manage Quizzes Screen. If you see a 0 or if the two numbers do not match, you will know that quiz attempts are not marked as graded.
To mark quiz attempts as graded select the drop down next to the quiz name and select Grade.
You have a choice to individually select an attempt by click the check box next to a quiz attempt or you can use the Select All icon to choose all attempts. If you use the select all option please make sure that all attempts are on a single page. You can use the Results Per Page drop down to increase the size.
Click Save and Close.
All quiz attempts should now be marked as graded.