Twitter bootstrap twitter引导警报不工作

我是新手。我想在加载时显示一个警报框。没有。这是jsfiddle。怎么了？谢谢

---

在这里工作，只需删除

div上的类
fade
#CanUseIPhoneAppPrompt

<div class="container">
    <div class="hero-unit">
        <h1>Bootstrap jsFiddle Skeleton</h1>
        <p>Fork this fiddle to test your Bootstrap stuff.</p>
        <p>
            <a class="btn btn-primary btn-large" href="http://twitter.github.com/bootstrap/index.html" target="_blank">
                Learn more about Bootstrap
            </a>
        </p>
    </div>
<div id="CanUseIPhoneAppPrompt" title="Please use the iPhone App." class="alert fade">    
      please try our iphone app                                      
</div>

$(function() {
    $("#CanUseIPhoneAppPrompt").alert();
});