Highlighting/Selecting grid row in ExtJS

I am newbie to Ext JS. I am working on a grid panel in which when I select/click any of the rows, then certain data related to the selected row is displayed in the panel below the grid. Also when the window is loaded the first should be selected/highlighted by default. Currently the grid & panel is displayed properly. Even the data related to the selected row is displayed in the panel but the row is not getting highlighted. I have tried the grid.focusRow(0) & grid.getRow(0).highlight() methods but they are not working. Below is my code.

//the js file code
initComponent : function() { //within the window instance

    var single = false;
    var store = new Ext.data.XmlStore({//all necessary fields added}); //store
    HttpUtil.syncCall(this.url, "GET", this.loadStore, store,this);
    var acctTplMarkup = [//the fields here are displayed on row selection ];
                /*The template for displaying the details of the selected row */
                 this.acctTpl = new Ext.Template(acctTplMarkup);
    //check for request type, if type is range of checks create the grid
    if (single == false) {
        var gridView = new Ext.grid.GridView();
        var colModel = new Ext.grid.ColumnModel([ {
            header : 'Status',
            dataIndex : 'status'
        }, {
            header : 'Message',
            dataIndex : 'message'
        } ]);
        var selModel = new Ext.grid.RowSelectionModel({
            singleSelect : true
        });
        grid = new Ext.grid.GridPanel({
                                          ...
                        listeners : {
                render : function(grid) {
                    Ext.getCmp('check').store.on('load',function(store, records, options) { //check is the id value for the window instance
                         grid.getSelectionModel().selectFirstRow(); 
                    });
                }
            }
    }); //gridPanel
    } //if