添加模态窗口的代码时，按钮将无法点击

Question

我有这个按钮来启动模态窗口

<a href="#" class="btn btn-success btn-wide" data-target="#myModal" data-toggle="modal"  >Launch Modal </a>

当我为模态窗口添加以下标记时（从bootstrap＆＃39; s站点本身复制），我无法点击按钮。当它被删除后，该按钮将再次被点击。

<div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
        <h4 class="modal-title" id="myModalLabel">Modal title</h4>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>