Publish to Facebook Wall with Graph & PHP

I'm having trouble using the open graph authorization to publish to the visitors facebook wall, and can't seem to figure out where I'm wrong. I'm using the P开发者_如何学运维HP/SDK Library from Github. Here's my code:

<?php
require_once('facebook.php');
$facebook = new Facebook(array(
  'appId'  => 'APP_ID',
  'secret' => 'APP_SECRET',
  'cookie' => true,
));

$session = $facebook->getSession();

$me = null;
//session-based api call
if ($session) {
  try {
    $uid = $facebook->getUser();
    $me = $facebook->api('/me');
  } catch (FacebookApiException $e) {
    error_log($e);
  }
}

//post to wall/stream function
if(isset($_POST['status'])) {
    try {
        $result = $facebook->api(
            '/me/feed',
            'post',
            array(
                'access_token' => 'ACCESS_TOKEN', 
                'message' => $_POST['status']
                )
            );
    } catch (FacebookApiException $e) {
        echo 'Error: ' . print_r($e, true);
    }
}
?>

<!-- HTML Form -->
<form name="" action="index.php" method="post">
    <input type="text" name="status" id="status" value="">
    <input type="submit" value="submit">
</form>

I don't know what's going on, I've combed through a billion tutorials, posts, exchanges, etc. and it seems like I'm doing everything right. Any help would be greatly appreciated.

Here you are not actually checking if the user is logged in before posting and I can't see where you are asking the user to login. Here's a better approach:

<?php
require_once('facebook.php');
$facebook = new Facebook(array(
  'appId'  => 'APP_ID',
  'secret' => 'APP_SECRET',
  'cookie' => true,
));

$session = $facebook->getSession();

if($session) {
    //post to wall/stream function
    if(isset($_POST['status'])) {
        try {
            $result = $facebook->api(
                '/me/feed',
                'post',
                array(
                    'message' => $_POST['status']
                    )
                );
        } catch (FacebookApiException $e) {
            echo 'Error: ' . print_r($e, true);
        }
    }
} else {
    $loginUrl = $facebook->getLoginUrl(array(
        'req_perms' => 'publish_stream'
    ));
    header("Location: $loginUrl");
}
?>

<!-- HTML Form -->
<form name="" action="index.php" method="post">
    <input type="text" name="status" id="status" value="">
    <input type="submit" value="submit">
</form>

With the code you've written, it is assumed that you are using the Javascript SDK to produce the facebook cookie, which is what the $facebook->getSession() call uses to log the user in: do you have the Javascript SDK setup correctly?

Also, you are assuming that whatever app you are using has obtained the appropriate permission to post to the user's wall. See http://developers.facebook.com/docs/authentication/permissions/ for more information about the required permissions. Have you obtained the requested permission from the user?