title: Messenger Platofrm subscribing app error: permission pages_messaging is required to register webhook
body: <p>From our app we want users to be able to authenticate with Facebook and to be able chat from within our app with their Facebook Page visitors (webhook / Send API).</p>
  
  <p>We are able to get the page access token, but are having trouble subscribing our Facebook app to the page using the page access token.</p>
  
  <p>The steps are as follows:</p>
  
  <ol>
  <li><p>User initiates authentication</p>
  
  <p><a href="https://www.facebook.com/dialog/oauth?client_id=[client_id]&amp;redirect_uri=[redirect_uri]&amp;state=[state]&amp;scope=publish_pages,manage_pages,pages_messaging" rel="nofollow">https://www.facebook.com/dialog/oauth?client_id=[client_id]&amp;redirect_uri=[redirect_uri]&amp;state=[state]&amp;scope=publish_pages,manage_pages,pages_messaging</a></p></li>
  <li><p>Exchange code for user access token</p>
  
  <p>/v2.7/oauth/access_token?client_id=[client_id]&amp;redirect_uri=[redirect_uri]&amp;client_secret=[client_secret]&amp;code=[code]</p></li>
  <li><p>Get Pages (and page access tokens) using user token</p>
  
  <p>/v2.7/me/accounts?access_token=[user_access_token]</p></li>
  <li><p>Subscribe our app to the Facebook Page using obtained page access token</p>
  
  <p>/v2.7/me/subscribed_apps?access_token=[page_access_token]</p></li>
  </ol>
  
  <p>This is where we are having trouble. The response from step 4 is:</p>
  
  <blockquote>
    <p>(#230) permission pages_messaging is required to register webhook for
    messages or deliveries</p>
  </blockquote>
  
  <p>All API calls are using v2.7 and the manage_pages, publish_pages and pages_messaging permissions have all been approved for the app.</p>
  
  <p>Any ideas or help on what we are missing?</p>