Instagram returning "Matching code was not found or was already used" when using OAuth
<p>I am trying to use the <strong>Instagram OAuth</strong> using the developer documentation at</p>

<p><a href="https://www.instagram.com/developer/authentication/">https://www.instagram.com/developer/authentication/</a>. </p>

<p>Step 1 and 2 are working without any problems, so I have my <code>Client-ID</code>, the <code>Client-Secret</code>, the <code>Redirect-URI</code> and the code. </p>

<p>But every-time I am trying to get the <code>Acces Token</code> I get the following error:</p>

<pre><code>{
"code": 400, 
"error_type": "OAuthException", 
"error_message": "Matching code was not found or was already used."
}
</code></pre>

<p>Any tips how to solve this?</p>