Only written shortcode is displayed

I use WordPress 4.2.3, SKT Full Width theme and FF 39 and the Plugin doesnt work for me at all. If I place a shortcode on a page, just the written shortcode is shown on the page, like \[sfp-page-plugin show_posts=true url=http://www.facebook.com/eventpho.to.JanSimecek]\

I don’t know, what I’m doing wrong, or what is wrong. The plugin is activated. But I can do only one thing with it, changing the language.

https://ww.wp.xz.cn/plugins/simple-facebook-plugin/