Not working on mobile browsers

Hi,
Thanks for such an easy-to-use plugin. I’ve setup this, and it seems to work on desktop browsers (I’ve visited on Windows). But the chat icon doesn’t show on mobile. I tried on Android Chrome, Firefox, IE, and the native Android browser build inside my phone. Could you help me get this solved?

Regards,
Arafat.

The page I need help with: [log in to see the link]