Erro com EXTJS

<script type="text/javascript">
/*
 * Ext JS Library 2.0
 * Copyright(c) 2006-2007, Ext JS, LLC.
 * [email removido]
 * 
 * http://extjs.com/license
 */

Ext.onReady(function(){

    Ext.state.Manager.setProvider(new Ext.state.CookieProvider());

    var myData = [
        ['','','Basico','',''],
        ['','','Intermediário','','']
    ];

    
    // create the data store
    var store = new Ext.data.SimpleStore({
        fields: [
           {name: 'excluir'},
           {name: 'alterar'},
           {name: 'nome'},
           {name: 'dataInicio'},
           {name: 'valorMin'}
        ]
    });
    store.loadData(myData);

    // create the Grid
    var grid = new Ext.grid.GridPanel({
        store: store,
        columns: [
            {header: "", width: 70, sortable: false, dataIndex: 'excluir'},
            {header: "", width: 70, sortable: false, dataIndex: 'alterar'},
            {header: "Nome do Perfil", width: 160, sortable: true, dataIndex: 'nome'}
            {header: "Início do Perfil", width: 85, sortable: true, dataIndex: 'dataInicio'}
            {header: "Valor Mínimo", width: 85, sortable: true, dataIndex: 'valorMin'}
        ],
        stripeRows: true,
        autoExpandColumn: 'nome',
        height:100,
        width:600,
        title:'Nível do Perfil do Investidor'
    });

    grid.render('grid-example');

    grid.getSelectionModel().selectFirstRow();
});

</script>