下拉刷新异常

做了一个下拉刷新功能，在边改边看模式中运行正常，但在真机（安卓）中报错
Uncaught TypeError: undefined is not a function at todolist.html:187

        if (mui.os.plus) {  
            mui.plusReady(function() {  
                setTimeout(function() {  
                    mui('#pullrefresh').pullRefresh().pullupLoading();  
                }, 1000);  
            });  
        } else {  
            mui.ready(function() {  
                mui('#pullrefresh').pullRefresh().pullupLoading();  
            });  
        }  

报错行是：mui('#pullrefresh').pullRefresh().pullupLoading();
why?????