My form won't scroll down on my website

http://ourlittleplanet.org/online-registration/

When I point my mouse on the form, it won't scroll but it works when you scroll outside the form or using the vertical scrollbar. 

Screencast:

I think the problem isn't with the form itself but with the custom scrollbar you're using. I would suggest to turn off the custom scroll plugin you have in your website and try it again. If that doesn't help, re-embed your form using iframe embed code. That might help.

Let us know if the issue still persists after that.

Regards!