It seems there is some jQuery conflict in your site. It is hard for me to say why it is exactly. What you need to do is, disable your other plugins one by one until the problem solves and then report here about the plugin which caused this problem. If the problem persists even after disabling all plugins, then the issue should be related to your theme.
I have tried it with 2 sites that I run with themes and it fails on both. This is a real shame as it looks such a great survey tool. Sadly I will have to find an alternative.
It would be great if you manages to work around the conflicting jQuery problems.