No Emma, i've never use manual grading, it was set for 100% but grades is over, i never happened before.
i tested the main problem is ... when the student already answered question, when they back to re-check their answer..it was gone !
so...in teacher / admin view, that student never leaved the log answer on that quiz, like the second picture that i posted yesterday in green circle, when i clicked review question the mssg is "Parameter missing"..
So server cannot take student's answer, but it calculated only once.
so i tested again, making all question in one page, it done very well, but the student's log answer still missing.
And i guess that grade is still over, a few but not all student.
Before all that problem happen, server shutdown improperly because electricity prob
and i cannot login before i repaired table on mdl_user, but when i'm in there's problem on this missing parameter on student log answer
i think.... what was happen ?
(sorry my english is so messy)