extaspnet的图片显示有关问题

extaspnet的图片显示问题
                        //定义刷新按钮
                        var refreshButton = new Ext.Button({
                            text: '刷新',
                            type: "button",
                            cls: "x-btn-text-icon",
                            icon: '<%= IconHelper.GetIconUrl(Icon.ArrowRefresh) %>',
                            listeners: {
                                click: function (button, e) {
                                    //注意：按钮的ownerCt是ToolBar，
                                    //按钮的ownerCt的ownerCt是当前活动的Tab
                                    //使用DomQuery查找到父项窗口并刷新页面
                                    Ext.DomQuery.selectNode('iframe',
                            button.ownerCt.ownerCt.getEl().dom).
                            contentWindow.location.replace(href);

                                    e.stopEvent();
                                }
                            }
                        });
为什么图片显示不出来
[解决办法]
去官网下例子吧