Hangouts shortcodes doesn´t work

Hello.

When I employ hangouts shortcodes, the button don´t appear, nothing apperas.

Here I have a page only with the tittle ‘Webinars’ and the shortcode ‘[sz-hangouts-start /]’:

http://www.sistemasdebolsa.com/premiumzone/webinars/

I deleted and download again and reinstall the plugin, try to create other pages and it didn´t work.

I observed that with other google tools like G+ the shortcodes works well.

Could anybodu help me? I have searching and I didn´t find anybody with the same problem.

Thanks in advance.

https://ww.wp.xz.cn/plugins/sz-google/