下拉菜单在单击可展开列表项时刷新

Question

当我点击下拉菜单中的“卧室”标签时，页面似乎刷新而不是展开/折叠以显示来宾/主卧。任何帮助都是极好的。

<!-- zone changer -->
        <ul class="nav navbar-nav navbar-left">
          <li class="dropdown">
            <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">
              AREA
              <span class="caret"></span>
            </a>
            <ul class="dropdown-menu dropdown-menu-left">
              <li><a href="#">Entrance</a></li>
              <li><a href="#">Living Room</a></li>
              <li><a href="#">Kitchen</a></li>
              <li class="nav-header"> <a href="#" data-toggle="collapse" data-target="#userMenu">Bedrooms <i class="glyphicon glyphicon-chevron-down"></i></a>
                    <ul class="nav nav-stacked collapse in" id="userMenu">
                        <li class="active"> <a href="#">Master Bedroom</a></li>
                        <li><a href="#">Guest Bedroom</a></li>
                    </ul>
              </li>
              <li><a href="#">Bathroom</a></li>
              <li><a href="#">Studio</a></li>
              <li><a href="#">Back Yard</a></li>
            </ul>
          </li>
        </ul>