Grade of new tests are zero!

Hi,

I was wondering why it takes so long to get a quiz-report. It was the picture that overviewgraph.php draws. There is a division by zero in line 60:
$bandwidth = $quiz->grade / $bands;
because $bands is by default zero.

Even when I change maxgrade by hand - I have to do it twice at first time.

After that, there's no division by zero and everything works fine!