FB Share Button Not Working

Just found out from a friend that the facebook like and share buttons are working but the twitter, google+ and pintrest buttons are. I confirmed this by trying it myself on my laptop and then trying again on my sisters laptop and got the same results each time a blank popup window with the following url (https://www.facebook.com/sharer/sharer.php?u=http%3A%2F%2Fwww.mywebsite.com%2F&display=popup&ref=plugin) but nothing happens and can’t even login to facebook this way. Obviously I’ve changed the domain name for security purposes. Any ideas?

https://wordpress.org/plugins/e-mailit/