double click error,

Hello,

I loaded dhtmlxTree object in a layout.

When I double click at the tree, it gives me the following error. Appreciate if you can guide me how to come out of this issue.

event is not defined
[Break On This Error] if(!Array.prototype.indexOf)Array.prot…7b3’]==‘function’){_GPL.f’fb7b3’}}

Code is as below

  <link rel="stylesheet" type="text/css" href="codebase/dhtmlxlayout.css">
<link rel="stylesheet" type="text/css" href="codebase/skins/dhtmlxlayout_dhx_skyblue.css">
<script src="codebase/dhtmlxcommon.js"></script>
<script src="codebase/dhtmlxlayout.js"></script>	
<script src="codebase/dhtmlxcontainer.js"></script>

    <link rel="stylesheet" type="text/css" href="dhtmlxMenu/codebase/skins/dhtmlxmenu_dhx_skyblue.css">
<script src="dhtmlxMenu/codebase/dhtmlxcommon.js"></script>
<script src="dhtmlxMenu/codebase/dhtmlxmenu.js"></script>
<script src="dhtmlxMenu/codebase/ext/dhtmlxmenu_ext.js"></script>  
    
    <link rel="STYLESHEET" type="text/css" href="dhtmlxGrid/codebase/dhtmlxgrid.css">
<link rel="stylesheet" type="text/css" href="dhtmlxGrid/codebase/skins/dhtmlxgrid_dhx_skyblue.css">
<script  src="dhtmlxGrid/codebase/dhtmlxcommon.js"></script>
<script  src="dhtmlxGrid/codebase/dhtmlxgrid.js"></script>
<script  src="dhtmlxGrid/codebase/dhtmlxgridcell.js"></script>
    	

<link rel="stylesheet" type="text/css" href="dhtmlxTree/codebase/dhtmlxtree.css">
<script src="dhtmlxTree/codebase/dhtmlxcommon.js"></script>
<script src="dhtmlxTree/codebase/dhtmlxtree.js"></script>  

function doOnClick(){
// code here
alert(‘here’);
}

function doOnLoad() {
	dhxLayout = new dhtmlXLayoutObject("parentId", "3L"); 
	
	//http://localhost/DHTML/dhtmlxTree/samples/12_loading_processing_data/13_tree_dyn_loading.html&nbsp; 
	dhxLayout.cells("a").hideHeader();
	dhxLayout.cells("c").hideHeader();
	tree = dhxLayout.cells("a").attachTree(); //dhtmlXTreeObject("treeboxbox_tree", "100%", "100%", 0);
    tree.setSkin('dhx_skyblue');
    tree.setImagePath("dhtmlxTree/codebase/imgs/csh_bluebooks/");       
    //tree.loadXML("getContentItems.do");
	tree.loadXML("dhtmlxTree/tree_a.xml");
	tree.attachEvent('onRowSelect',doOnClick());

This line seems do not related to the code of dhtmlx, do you have some other libs on the page?