If you encounter the error above, you can check if the issue is caused by a plugin conflict or a theme. In order to test, you need to deactivate plugins one by one and check your page if the quiz shows. Also changing the theme to default Twenty Twelve will also if if VQB has conflict with your theme.
If you still can't get the issue fixed, you can send us a ticket along with your site URL and wp-admin details for us to check.
Below are common plugins that conflict with VQB
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