I downloaded this plugin about two weeks ago and let it run without the App for a while - because I'm just learning to be 'tekky' and thought configuring the app would be too hard for me!.
Initially, the steps I took was to delete all other Facebook icons - then using Jetpack's 'sharing' section from wordpress.com dragged and dropped the social tabs wanted.
I also disabled the WP comment box as per the instructions. The FB Comments box worked, but without the app it wouldn't show the 'comment moderation area'.
So I followed the instructions for the app and used 'Heroku'. The only issue I found was that when setting it up the boxes get automatically filled in and one had to delete that info and replace it with one's own website address. [It was during this process that a notice came up saying there was an error.]
I followed through with the instructions and now the comment box moderation area is active. However, the comment box does not show up in IE at all. It shows fine in Chrome.
I've just written about the above in case it jogs a memory or helps someone to get there's working better.
'Diegocerezom' is sounds as though you have not configured the app.
Does anyone know why it doesn't show up in IE?