twitter-bootstrap – 如何为“nav-pills”和“nav-stacked”显

<div class="container">

<div class="row">
    <div class="col-sm-3">
        <ul class="nav nav-pills nav-stacked">
            <li><a href="#">Available glyphs</a></li>
            <li class="disabled"><a href="#">How to use</a></li>
            <li><a href="#">Examples</a></li>
            <li class="divider"></li>
            <li><a href="#">Example</a></li>
        </ul>
    </div>
    <div class="col-sm-3">
        <ul class="nav nav-pills nav-stacked">
            <li><a href="#">Basic example</a></li>
            <li><a href="#">Vertical variation</a></li>
            <li class="divider"></li>
            <li><a href="#">Single button dropdowns</a></li>
        </ul>
    </div>
    <div class="col-sm-3">
        <ul class="nav nav-pills nav-stacked">
            <li><a href="#">Basic example</a></li>
            <li><a href="#">Checkboxes and radio addons</a></li>
            <li class="divider"></li>
            <li><a href="#">Justified</a></li>
        </ul>
    </div>
    <div class="col-sm-3">
        <ul class="nav nav-pills nav-stacked">
            <li><a href="#">Fixed to bottom</a></li>
            <li><a href="#">Static top</a></li>
            <li><a href="#">Inverted navbar</a></li>
        </ul>
    </div>
</div>

class“divider”不起作用。我错过了什么吗？

http://jsfiddle.net/isherwood/B9gHc