title: Facebook API {"error":{"message":"(#100) No matching user found","type":"OAuthException" Checkbox Plugin
body: <p>I am trying to use the feature of the checkbox plugin. I manage to make the checkbox rendered. A few days ago, I managed to send some basic text 'Hello World' to the user. But now I'm not able to send anything thing. Whenever I tried to send to the user I get this error:</p>
  
  <pre><code>{"error":{"message":"(#100) No matching user found","type":"OAuthException","code":100,"error_subcode":2018001,"fbtrace_id":"HCZPBkofiz9"}}
  </code></pre>
  
  <p>I even try to cURL using, but no success, still the same error.</p>
  
  <pre><code>curl -X POST -H "Content-Type: application/json" -d '{
    "recipient": {
        "user_ref":"&lt;UNIQUE_REF_PARAM&gt;"
    }, 
    "message": {
        "text":"hello, world!"
    }
  }' "https://graph.facebook.com/v2.6/me/messages?access_token=&lt;PAGE_ACCESS_TOKEN&gt;" 
  </code></pre>
  
  <p>What I've done are:</p>
  
  <ol>
  <li>Uninstalled app from the page.</li>
  <li>Select the page again and generate new PAGE_ACCESS_TOKEN.</li>
  <li>Subscribe to messages, messaging_postbacks, messaging_optins webhooks to the page.</li>
  <li>Set the new token in .env.</li>
  <li>Save up the new user_ref through checkbox plugin.</li>
  <li>Try cURL by using the new user_ref, no luck.</li>
  </ol>
  
  <p>I am able to send with recipient senderID but not user_ref for checkbox plugin.</p>
  
  <p>Any help is very much appreciated :)</p>