ExtJS GridPanel & ldquo; Show in groups & rdquo; Not displayed / not working


I encountered some weird behavior on GridPanel feature of ExtJs. I have included a groupField config option and it is not displayed and as well not working. Maybe you guys can give me an idea why?

createStore : function(itemPath) {
                        return new

                                 proxy : new CQ.Ext.data.HttpProxy(
                                                url : "/bin/test/private/folder/check.json",
                                                method : "GET"
                                //method: "GET",
                                reader: new CQ.Ext.data.JsonReader({
                                        root: 'variables',
                                        fields: [
                                            {name: 'group', type: 'string'},
                                            {name: 'path', type: 'string'},
                                            {name: 'status', type: 'string'}
                              updateData : function() {

                                    // request the data
                                        params : {
                                            path : itemPath
                                sortInfo: {field: 'path', direction:'ASC'},
                                groupField: 'group',
                                groupOnSort: true,
                                autoLoad : true

If you want your groups to be displayed in the grid panel, you also need to add the grouping feature to your grid.