Google ReCaptcha不会在Safari 5.1.10中显示

Question

您好我有Google ReCaptcha的代码：

<div class="captcha">
<script type="text/javascript"
 src="https://www.google.com/recaptcha/api/challenge?k=code">
 </script>
 <noscript>
 <iframe src="https://www.google.com/recaptcha/api/noscript?k=6code"
     height="300" width="500" frameborder="0"></iframe><br>
 <textarea id="recaptcha_challenge_field" name="recaptcha_challenge_field" rows="3"  cols="40">
 </textarea>
 <input type="hidden" name="recaptcha_response_field"
     value="manual_challenge">
 </noscript>

 </div>

但这不会在Safari Mac 5.1.10 Snow Leopard中显示。只有重新加载后才显示Captcha。