下拉刷新，安卓报错，求解决

mui('#pullrefresh').pullRefresh({  
      down: {  
        callback: function() {  
          ...  
        }  
      },  
      up: {  
        contentrefresh: '正在加载...',  
        callback: function() {  
          ...  
        }  
      }  
    })

问题用这种写法设置下拉刷新－安卓会报错 “Uncaught TypeError: Cannot read property 'down' of undefined”
求解决