title: "An access token is required to request this resource" while accessing an album / photo with Facebook php sdk
body: <p>I am using the php sdk to access a user's albums and photos in a website.
  I am able to login and also able to retrieve all the info about the albums and photos.</p>
  
  <p>However, I am not able to display these photos on the webpage.</p>
  
  <p>When I try the graph API, to get the photo / album like below: </p>
  
  <pre><code>https://graph.facebook.com/131833353530147/picture
  </code></pre>
  
  <p>I get the following error message:</p>
  
  <pre><code>{
     "error": {
        "type": "OAuthException",
        "message": "An access token is required to request this resource."
     }
  }
  </code></pre>
  
  <p>But the same is working in while I try to display my profile pic and I do have a valid access token.</p>
  
  <p>Help on this would be greatly appreciated.</p>