mui 轮播组件无法自动轮播，默认展示最后一张图片，第一次手动滑动时自动滑动正常。请教大神们。

                                    <div class="mui-collapse-content">  
                        <div class="mui-slider" id="slider">  
                          <div class="mui-slider-group mui-slider-loop">    

                            <div class="mui-slider-item mui-slider-item-duplicate">  
                                <a href="#"><img src="img/44.jpg"/></a>  
                            </div>  
                            <!--第一个内容区容器-->  
                            <div class="mui-slider-item mui-active">  
                              <a href="#"> <img src="img/22.jpg"/> </a>  
                            </div>  
                            <!--第二个内容区-->  
                            <div class="mui-slider-item">  
                              <a href="#"> <img src="img/33.jpg"/></a>  
                            </div>  
                            <!--第三个内容区-->  
                            <div class="mui-slider-item">  
                                <a href="#"><img src="img/44.jpg"/></a>  
                            </div>  

                            <div class="mui-slider-item mui-slider-item-duplicate">  
                              <a href="#"> <img src="img/22.jpg"/> </a>  
                            </div>  
                          </div>  
                          <!--指示器-->  
                          <div class="mui-slider-indicator">  
                            <div class="mui-indicator mui-active"></div>  
                            <div class="mui-indicator"></div>  
                            <div class="mui-indicator"></div>  
                          </div>  
                        </div>  
                    </div>  

js：
<script type="text/javascript">
mui.init();
mui(".mui-slider").slider({interval:2000});
</script>

浏览器报错：
[Web浏览器] "Uncaught TypeError: Cannot read property '0' of undefined" /test/js/mui.js (4994)