title: verify recaptcha is correct with PHP returning false
body: <p>I am trying to verify recaptcha is correct but it's always false and recaptcha_challenge_field and recaptcha_challenge_field is always null on a var_dump. I am using the public key as it is asked in the code:</p>
  
  <p>html:</p>
  
  <pre><code>&lt;script type="text/javascript" src="http://www.google.com/recaptcha/api/challenge?
  k=your_public_key_here"&gt;&lt;/script&gt;
  &lt;noscript&gt;&lt;iframe src="http://www.google.com/recaptcha/api/noscript?k=your_public_key_here"
  height="300" width="500" frameborder="0"&gt;&lt;/iframe&gt;&lt;br&gt;
  &lt;textarea name="recaptcha_challenge_field" rows="3" cols="40"&gt;
  &lt;/textarea&gt;
  &lt;input type="hidden" name="recaptcha_response_field" value="manual_challenge"&gt;
  &lt;/noscript&gt;
  </code></pre>
  
  <p>my php:</p>
  
  <pre><code>require_once('recaptchalib.php');
  $privatekey = "**************************************";
  $publickey = "**************************************";
  
  $resp = recaptcha_check_answer(
      // $privatekey,
      $publickey, //changed this to public 
      $_SERVER["REMOTE_ADDR"],
      $_POST["recaptcha_challenge_field"],
      $_POST["recaptcha_response_field"]
  );
  
  var_dump($resp); 
  var_dump($_POST["recaptcha_challenge_field"]);//null
  var_dump($_POST["recaptcha_response_field"]); //null
  
  if (!$resp-&gt;is_valid) {
      die( "The reCAPTCHA wasn't entered correctly. Go back and try it again." .
      "(reCAPTCHA said: " . $resp-&gt;error . ")" );
  } else {
      die( "The reCAPTCHA is correct.");
  }
  </code></pre>
  
  <p>var_dump on the $resp gives me:</p>
  
  <pre><code>object(ReCaptchaResponse)#610 (2) { ["is_valid"]=&gt; bool(false) ["error"]=&gt; string(21) "incorrect-captcha-sol"}
  </code></pre>
  
  <p>What am I doing wrong here? Thanks.</p>