ExtJS网格不会排序

我在ExtJS3.4中有一个网格，但它不会排序。单击列标题时，我在firebug中遇到此错误：

Array.prototype.sort参数无效

第48523行

我怎么修理它

以下是存储、列和网格定义：

function AircraftFeesStore() {
    return new Ext.data.JsonStore(Ext.apply({
        url: AVRMS.ROOT_CONTEXT + "/ssl/json/general/GetAircraftFees.aspx",
        idProperty: 'AircraftOid',
        baseParams: {
            OwnerOid: 0,
            SelectedAircraft: ''
        },
        fields: ['AircraftOid','NNumber', 'Make', 'Model', 'RegistrationFeeFormatted']
    }));
}   

var colModel = new Ext.grid.ColumnModel([
        { id: 'AircraftOid', width: 100, sortable: true, locked: true, hidden: true, dataIndex: 'AircraftOid' },
        { header: "N-Number", width: 100, sortable: true, hidden: true, dataIndex: 'NNumber' },
        { header: "Make", width: 250, sortable: true, hideable: false, dataIndex: 'Make' },
        { header: "Model", width: 250, sortable: true, hideable: false, dataIndex: 'Model' },
        { header: "Registration Fee", width: 150, sortable: true, hideable: false, dataIndex: 'RegistrationFeeFormatted' }
    ]); 


var registrationGrid = new Ext.grid.GridPanel(
    {
        store: aircraftFeesStore,
        cm: colModel,
        sm: new Ext.grid.RowSelectionModel({ singleSelect: true }),
        viewConfig: {
            forceFit: true
        },
        width: 970,
        height: 150,
        split: true,
        region: 'north',
        frame: true,
        title: 'Selected Aircraft with Total'
    }); 

试着给予

remoteSort:true

在你的格子里