Blank admin screen

I’m getting a blank admin area when trying to activate the plugin. At the top of the screen is “You are just 30 sec away from boosting your blog with ratings…”
I can see that it is trying to load an admin iframe source:
https://secure.rating-widget.com/signup/wordpress/#http%3A%2F%2Fmywebsiteurl.com%2Fwp-admin%2Fadmin.php%3Fpage%3Dratingwidget

I can also see that the page is “loading” but all of the content is hidden.

I suspect it has to do with the secure nature of the URL https://secure.rating-widget.com/signup/wordpress

Any ideas??

Fresh installation of 2.0.8
WordPress 3.9.1

https://ww.wp.xz.cn/plugins/rating-widget/