I had a look at your link, and noticed several JavaScript errors in the console. I suspect these errors are responsible for the trouble.
The first thing to check is whether any other plugins on your site may have a conflict. Please check our Known Issues list here:
https://jetpack.me/support/getting-started-with-jetpack/troubleshooting-tips/
You can also try to deactivate all plugins on your site, and see if that resolves the issue. If it does, then activate them one at a time to determine which is causing the conflict.
If that doesn’t help, please rule out a theme conflict by temporarily changing your site’s theme to a default theme (such as Twenty Fifteen) and trying again.
Please let me know how that works for you, and we can go from there!