Ext4.0.7使用Ext.grid.ColumnModel报错：TypeError: Ext.grid.Model is not a constructor

代码如下：

Ext.onReady(function(){
    　　　　　　　//定义列
                var cm = new Ext.grid.ColumnModel([
                    {header: '编号', dataIndex: 'id'},
                    {header: '名称', dataIndex: 'name'},
                    {header: '描述', dataIndex: 'des'}
                ]);
                
                //数据定义
                var data = [
                    ['1001','name1','description1'],
                    ['1002','name1','description1'],
                    ['1003','name1','description1'],
                    ['1004','name1','description1'],
                    ['1005','name1','description1']
                ];
                
                //数据源定义
                var store = new Ext.data.Store({
                    proxy: new Ext.data.MemoryProxy(data),
                    reader: new Ext.data.ArrayReader({},[
                        {name: 'id'},
                        {name: 'name'},
                        {name: 'des'}
                    ])
                });
                store.load();
                
                //grid panel
                var grid = new Ext.grid.GridPanel({
                    renderTo: Ext.getBody(),
                    store: store,
                    cm: cm
                });
});

google了一下：In Extjs 4.0 ,there is no colModel config for GridPanel(http://www.sencha.com/forum/showthread.php?199720-Ext.grid.ColumnModel-is-not-a-constructor)然后查看其API：其用法如下

Ext.onReady(function(){
　　　　　　　　Ext.create('Ext.data.Store', {
                    storeId: 'simpleStore',
                    fields: ['name', 'email', 'phone'],
                    data:{
                        'items':[
                            {'name':'yanshiying', 'email':'email', 'phone':'1234567890'},
                            {'name':'yanshiying', 'email':'email', 'phone':'1234567890'},
                            {'name':'yanshiying', 'email':'email', 'phone':'1234567890'}
                        ]
                    },
                    proxy: {
                        type: 'memory',
                        reader: {
                            type: 'json',
                            root: 'items'
                        }
                    }    
                });
                
                Ext.create('Ext.grid.Panel', {
                    title: 'Simple',
                    store: Ext.data.StoreManager.lookup('simpleStore'),
                    columns: [
                        {header: 'Name', dataIndex: 'name'},
                        {header: 'Email', dataIndex: 'email'},
                        {header: 'Phone', dataIndex: 'phone'}
                    ],
                    height: 200,
                     400,
                    renderTo: Ext.getBody()
                });
})

运行效果：