为什么a标签中的img图片显示不出来呢

Question

<div class="index-panel-body index-pics clearfloat">

            <a class="pic-col pic-col-m"><img src="image/pic-m.jpg" alt=""></a>
            <div class="pic-col pic-col-s">
                <a class="pic-row"><img src="image/pic-s1.jpg" alt=""></a>
                <a class="pic-row"><img src="image/pic-s2.jpg" alt=""></a>
            </div>
            <a class="pic-col pic-col-l"><img src="image/pic-l.jpg" alt=""></a>
        </div>

/css/

.index-pics {
    height: 380px;
    overflow: hidden;
}

.index-pics .pic-col {
    float: left;
}

.index-pics .pic-col-m {
    width: 354px;
}

.index-pics .pic-col-s {
    width: 287px;
}

.index-pics .pic-col-l {
    width: 460px;
}