尝试集成facebook PHP SDK时出现PHP错误

我是PHP的新手，并且绑定了一个页面，以便用户可以使用Facebook PHP SDK和JavaScript SDK登录。我一直收到休耕错误，似乎找不到解决方案。我在这里看到了类似的帖子，但我无法给出错误的解决方案。

解析错误：语法错误，意外T_STRING，第 2 行/homepages/9/d321009915/htdocs/kno_login/login.php 中预期"，"或";">

这是我的代码：

<?php
echo '<div id='fb-root'></div>';
require_once("facebook.php");
$config = array();
$config['appId'] = 'some id';
$config['secret'] = 'something here';
$facebook = new Facebook($config);
?>

<script>
  window.fbAsyncInit = function() {
  FB.init({
    appId      : '293441190799565', // App ID
    channelUrl : '//www.reyesmotion.com/kno_login/channel.html', // Channel File
    status     : true, // check login status
    cookie     : true, // enable cookies to allow the server to access the session
    xfbml      : true  // parse XFBML
  });
  // Here we subscribe to the auth.authResponseChange JavaScript event. This event is fired
  // for any authentication related change, such as login, logout or session refresh. This means that
  // whenever someone who was previously logged out tries to log in again, the correct case below 
  // will be handled. 
  FB.Event.subscribe('auth.authResponseChange', function(response) {
    // Here we specify what we do with the response anytime this event occurs. 
    if (response.status === 'connected') {
      // The response object is returned with a status field that lets the app know the current
      // login status of the person. In this case, we're handling the situation where they 
      // have logged in to the app.
      testAPI();
    } else if (response.status === 'not_authorized') {
      // In this case, the person is logged into Facebook, but not into the app, so we call
      // FB.login() to prompt them to do so. 
      // In real-life usage, you wouldn't want to immediately prompt someone to login 
      // like this, for two reasons:
      // (1) JavaScript created popup windows are blocked by most browsers unless they 
      // result from direct interaction from people using the app (such as a mouse click)
      // (2) it is a bad experience to be continually prompted to login upon page load.
      FB.login();
    } else {
      // In this case, the person is not logged into Facebook, so we call the login() 
      // function to prompt them to do so. Note that at this stage there is no indication
      // of whether they are logged into the app. If they aren't then they'll see the Login
      // dialog right after they log in to Facebook. 
      // The same caveats as above apply to the FB.login() call here.
      FB.login();
    }
  });
  };
  // Load the SDK asynchronously
  (function(d){
   var js, id = 'facebook-jssdk', ref = d.getElementsByTagName('script')[0];
   if (d.getElementById(id)) {return;}
   js = d.createElement('script'); js.id = id; js.async = true;
   js.src = "//connect.facebook.net/en_US/all.js";
   ref.parentNode.insertBefore(js, ref);
  }(document));
  // Here we run a very simple test of the Graph API after login is successful. 
  // This testAPI() function is only called in those cases. 
  function testAPI() {
    console.log('Welcome!  Fetching your information.... ');
    FB.api('/me', function(response) {
      console.log('Good to see you, ' + response.name + '.');
    });
  }
</script>
<!--
  Below we include the Login Button social plugin. This button uses the JavaScript SDK to
  present a graphical Login button that triggers the FB.login() function when clicked.
  Learn more about options for the login button plugin:
  /docs/reference/plugins/login/ -->
<?php
echo '<fb:login-button show-faces="true" width="200" max-rows="1"></fb:login-button>';
?>