问jQuery jqGrid TreeGrid未正常工作

EN

jQuery(function(){

  var gridOptions = {
    datatype: "local",
    height: 250,
    colNames: ['Name', 'Type', 'Last Modified On', 'Last Modified By'],
    colModel: [{name: 'name', index: 'name', width: 200, sorttype: 'text'},
           {name: 'type', index: 'type', width: 200, sorttype: 'text'},
           {name: 'modifiedon', index: 'modifiedon', width: 200, sorttype: 'date'},
           {name: 'modifiedby', index: 'modifiedby', width: 200, sorttype: 'text'}],
    treeGrid: true,
    ExpandColumn: 'name',
    caption: "My Grid"
};

    jQuery("#treeGrid").jqGrid(gridOptions);

var gridData = [
    {name: "My File", type: "My File Type", modifiedon: "03/10/2010", modifiedby"Strong Sad", lft: "1", rgt: "8", level: "0"},
    {name: "One of Everything", type: "Word Document", modifiedon: "02/12/2009", modifiedby: "Strong Bad", lft: "2", rgt: "5", level: "0"},
    {name: "My Presentation", type: "PowerPoint", modifiedon: "01/23/2009", modifiedby: "The Cheat", lft: "3", rgt: "4", level: "0"}
];

for (var i = 0; i < gridData.length; i++) {
    jQuery("#treeGrid").jqGrid('addRowData', i + 1, gridData[i]);
}

});