Invalid Token error

I can't play the quiz. I get "Invalid Token or (May be Session Expire)" 9 out of 10 times. I have tried disabling all third-party plugins and modules on the VQuiz page, but nothing works.Clearing the site and cache browser doesn't help either.
I don't see a javascript error in firebug.
Basically VQuiz doesn't work.
Here is the link:
observer.ug/quiz/quizzes/current-affairs...now-mugabe/play.html

Hello,
I apologize for the inconvenience caused. It definitely seems to be an issue with the Quiz settings. Please share your backend & FTP login credentials via Contact us form, We'll look into it.