The "Subscribe" button for my newsletter doesn't work..

The "Subscribe" button for my newsletter doesn't work.. It's not functional, once clicked, it doesn't do anything. I used the shortcode of the plugin and paste it on the pop up.

Here's the link for the page: http://wavesofdentists.com/add-a-listing/

You might be needing proxy to access this US based site. Just wait a few seconds once the page loads, a pop up with the opt-in form will appear, try testing the form and hit Subscribe button, nothing will happen.

I'll wait for your response.

Thanks