how can I count the likes for posts via my app?

I have an app, the app allows users to post on their walls, these posts are likable, how can my app get all the likes for posts the users made via the app even if the users set the post to non-public?

I've tried doing:

$response = $facebook->api('/APPID/posts');

and nothing, blank array.

Also trie开发者_JS百科d:

 $response = $facebook->api('/POSTID');

And works only if the post is set to public.

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how can my app get all the likes for posts the users made via the app even if the users set the post to non-public?

It's not possible