ExtJs 4 grid.Panel Ajax代理不显示数据

Question

这是我的代码：

    var operation = new Ext.data.Operation({
            action: 'read',
        });


        var proxy = new Ext.data.proxy.Ajax({
                url: '/myurl/services',
        });


        var reader = new Ext.data.JsonReader({
            idProperty: 'id', 
            root: 'services',
            type: 'json',
            fields: [
                {name: 'id', mapping: 'id'},
                {name: 'title', mapping: 'title'}
            ]
        });


        var store = new Ext.data.Store({
            idProperty: 'id',
            storeId: 'store',
            proxy:  proxy,
            reader: reader,
        });

        var servicesGrid=Ext.create('Ext.grid.GridPanel',{
            store: companyservicesstore,
            columns: [
            {header: "id", width: 150, hidden:true, sortable: true, dataIndex: 'id'},
            {header: "Titolo", width: 200, sortable: true, dataIndex: 'title' }
        ],
            columnWidth: 0.60,
            tbar: true,
            region: 'center',
            border: true,
            selType: 'rowmodel'
        });

proxy.read(operation);

结果是一个空格...请求没问题，但数据没有呈现......

感谢