Ext.ux.data.PagingMemoryProxy为空或不是对象

不知道哪里写的不对了 请教牛人
var underTheData = [
['笔记本', 'bijiben', '电脑'],
['台式机', 'taishiji', '电脑']
];
var store = new Ext.data.Store({
proxy: new Ext.ux.data.PagingMemoryProxy(underTheData),
remoteSort:true,
reader: new Ext.data.ArrayReader({
fields: [
            {name: 'dataName'},
             {name: 'dataCode'},
             {name: 'parentMarker'}
]
})
});

store.load({params:{start:0, limit:15}});

//创建checkbox
this.underTheDataSm = new Ext.grid.CheckboxSelectionModel();

//创建列模型
this.underTheDataCm = new Ext.grid.ColumnModel([
new Ext.grid.RowNumberer(),// 获得行号
this.underTheDataSm,//checkbox
            {id:'dataName', header: "数据字典名称", width: 100, sortable: true, align: "center",dataIndex: 'dataName'},
            {id:'dataCode', header: "数据字典编码", width: 100, sortable: true, align: "center",dataIndex: 'dataCode'},
            {id:'parentMarker', header: "父节点标识", width: 100, sortable: true, align: "center", dataIndex: 'parentMarker'}
]);

//创建查询列表
this.underTheDataGridPanel = new Ext.grid.GridPanel({
store: store,
cm: this.underTheDataCm,
sm: this.underTheDataSm,
loadMask: true,
autoScroll: true,
border: false,
height: 600,
collapsible: true,//设置面板可收缩
tbar: this.underTheDataTopToolBar,
bbar: new Ext.PagingToolbar({
pageSize: 15,
store: store,
displayInfo: true,
plugins: new Ext.ux.ProgressBarPager()
})
});
var underTheDataFieldSet = new Ext.form.FieldSet({
title: "下属数据信息",
autoHeight: true,
collapsible: true,
items: [this.underTheDataGridPanel]
});
dataDictTabPanel.superclass.constructor.call(this,{
labelAlign: "right",
buttonAlign: "right",
frame: true,
bodyStyle: "padding:0 0",
autoScroll: true,
items: [
dataDictInfoFieldSet, dataDictAddFieldSet, underTheDataFieldSet
]
});