Have you tried using your error console (F12)?
BTW, when posting here please help us to help you by making it easier to copy, test and debug your scripts by following the posting guidelines and wrapping your code in CODE tags. This means use the octothorpe or # button on the toolbar. You can (and should) edit your previous post.
Quizmaster: Which Russian leader is credited as the architect of glasnost?
All the code given in this post has been tested and is intended to address the question asked.
Unless stated otherwise it is not just a demonstration.