time axis renderer not working?

Code:

    items: [{
        xtype: 'panel',
        bind: {
            title: '{name}'
        },
        region: 'west',
        html: '<ul><li>This area is commonly used for navigation, for example, using a "tree" component.</li></ul>',
        width: 250,
        split: true,
        tbar: [{
            text: 'Button',
            handler: 'onClickButton'
        }]
    },{
        region: 'center',
        xtype: 'tabpanel',
        items:[{
            /*
            title: 'Tab 1',
            html: '<h2>Content appropriate for the current navigation.</h2>'
            */
            xtype:"chart",


          layout:'fit',
          store:{
            fields:[{name:"date",type:"date"},{name:"count",type:"int"}],
            data:[
              {'date':'2014/06/01','count':5}
              ,{'date':'2014/06/02','count':20}
              ,{'date':'2014/06/03','count':10}
              ,{'date':'2014/06/04','count':15}
              ,{'date':'2014/06/05','count':5}
              ,{'date':'2014/06/06','count':10}
              ,{'date':'2014/06/07','count':25}
            ]
          },
          interactions:[{
            type:"panzoom",
            zoomOnPanGesture: true
          }],
          axes: [{
            type: 'numeric',
            fields:['count'],
            position: 'left',
            minimum:0,
            grid:true,
            renderer:function(v){
              console.log(v);   //  <- is Working!!
              return v;
            }
          }, {
            type: 'time',
            fields:['date'],
            position: 'bottom',
            dateFormat:'Y-m-d',
            grid:true,
            step:[Ext.Date.DAY, 1],
            label: {
                rotate: {
                    degrees: -90
                }
            },
            renderer:function(v){
              console.log(v);  // <-- is not Working
              return v;
            }            
          }],
          series:[{
            type: 'line',
            xField: 'date',
            yField: 'count',
            fill:true,
            style:{
              lineWidth:2
            }
          }]
            
        }]
    }]