[Plugin: Facebook comments for WordPress] Invalid application ID

Hi,
I installed this plugin, created a new app for it on facebook, copy-paste app ID and secret keys. But it always shows me message:

ERROR! Invalid application ID. Please double check to make sure it is correct. Note that this is not the same thing as your Facebook user ID

Where can be the problem? I am using newest version of wordpress and plugin.

On my page it’s showing only like button and thats everything.

Thanks for help