Only the moderators of the application can like / comment posts on WordPress sit

I implemented Facebook like button and comments box on my WordPress site.

I created the Facebook application and provided the Application ID and the Secret Key in the plugin settings.

The comments box and like button appear on the post pages. I can like posts and comment via Facebook but the others cannot. I am the admin on the Facebook application and I believe that this is related to this.

My brother who tested (he’s not admin) gets this request response when he tries to leave a comment via Facebook Comments Box (in the UI no error is displayed):

{
“__ar”: 1,
“error”: 1340004,
“errorSummary”: “You are not connected”,
“errorDescription”: “You are not connected. Connect and then try again.”,
“payload”: null,
“bootloadable”: {},
“ixData”: []
}

(the error messages appear in Romanian but I translated them in English. I am not sure they are exactly correct).

How can I fix the problem?

https://wordpress.org/plugins/facebook/
http://wordpress.stackexchange.com/q/141140/44849