左右控制器 为什么不在图片内部显示

  <div id="slidershow" class="carousel">
    <ol class="carousel-indicators">
        <li class="active">1</li>
        <li>2</li>
        <li>3</li>
    </ol>
    <!-- 设置轮播图片 -->
    <div class="carousel-inner">
        <div class="item active">
            <a href="##"><img src="http://images3.c-ctrip.com/rk/201407/ll580x145.jpg" alt=""></a>
            <div class="carousel-caption">
                <h3>图片标题1</h3>
                <p>描述内容1...</p>
            </div>
        </div>
        <div class="item">
            <a href="##"><img src="http://images3.c-ctrip.com/dj/201408/zj/zj_580145.jpg" alt=""></a>
            <div class="carousel-caption">
                <h3>图片标题2</h3>
                <p>描述内容2...</p>
            </div>
        </div>
        <div class="item">
            <a href="##"><img src="http://images3.c-ctrip.com/dj/201408/zqgq_580145.jpg" alt=""></a>
            <div class="carousel-caption">
                <h3>图片标题3</h3>
                <p>描述内容3...</p>
            </div>
        </div>
    </div>
    <a calss="left carousel-control" href="">
        <span class="glyphicon glyphicon-chevron-left"></span>
    </a>
  </div>

这样写有什么问题吗    是放在carousel容器里了啊