Facebook button not showing

The Facebook button is not showing in my case. The “Close” button is showing and I can customise it.

See problem here:
http://wpwalkthechat.staging.wpengine.com/
(display on all pages + test mode)

I am using WordPress 4.1.1. Hope this can be fixed as this plugin looks great otherwise!

Thanks a bunch,

Thomas

https://ww.wp.xz.cn/plugins/popups/