I reviewed the capabilities of the graduate role and found that role mod/quiz:reviewmyattempt was set to prohibit. I don't know how I missed this setting . Anyway, after setting the mod/quiz:reviewmyattempt to allow it worked.
Thanks a lot
PS: I have a similar issue in lesson which I did not want to ask here, so I have added a new discussion- https://moodle.org/mod/forum/discuss.php?d=244165 . I have searched for settings similar to quiz, but unfortunately no luck.