I had a look at your site, and you seem to be using the Disqus plugin to handle comments on your site. You’ll only be able to use one Comments plugin at a time, so you’ll need to deactivate Disqus if you want to use Jetpack Comments.
If that doesn’t help, you’ll need to check how your theme’s comments.php is built.
Jetpack Comments relies on the comment_form() function being used to display the comment form. Unfortunately, some themes still hard code a comment form instead of using this function.
If your theme hard codes the comment form, you or the theme author will need to replace it with comment_form() in order for Jetpack Comments to work correctly.
You can read more about this function here:
Let me know if it helps.
