GET facebook group feed on 2.8

I have a problem with facebook graph api in accessing user group.

If i access directly with this: https://graph.facebook.com/fb_id/groups?access_token=token

I can access and retrieve group that i manage only.

other group i join as member not showing on graph

i have already tried

try {$response = $fb->get('/me/$groupid', $pageAccessToken);}

catch(Facebook\Exceptions\FacebookResponseException $e) {

echo 'Graph returned an error: '.$e->getMessage();

the result is same.. May I know what went wrong here?