Swapping in treeview gives error

[Heamraj]

I am dragging items between the nodes. I am getting the error if i swap two nodes on the same level. could any one help me. The sample code is here. I have tested with 3 levels of nodes

 

    <script language="javascript" type="text/javascript">

                function onNodeDropping(sender, args)
                {
                    var dest = args.get_destNode();
                    if (dest)
                    {
                            clientSideEdit(sender, args);
                            args.set_cancel(true);
                            return;

                        //dropOnTree(args);
                    }
                    else
                    {
                        dropOnHtmlElement(args);
                    }
                }


                function clientSideEdit(sender, args)
                {
                    if(isValidDrop(sender,args)==false)
                    {
                        args.set_cancel(true);

                        return;
                    }
var destinationNode = args.get_destNode();
    if(destinationNode)
    {
        var firstTreeView = $find('trvOne');
        var secondTreeView = $find('trvOne');

        firstTreeView.trackChanges();
       // secondTreeView.trackChanges();
        var sourceNodes = args.get_sourceNodes();

            var sourceNode = sourceNodes[0];
            sourceNode.get_parent().get_nodes().remove(sourceNode);

            //if(args.get_dropPosition() == "over") destinationNode.get_nodes().add(sourceNode);
            //if(args.get_dropPosition() == "above")  insertBefore(destinationNode, sourceNode);
            //if(args.get_dropPosition() == "below")  insertAfter(destinationNode, sourceNode);
            insertBefore(destinationNode, sourceNode);
            //sourceNode.clone();

        destinationNode.set_expanded(true);

        firstTreeView.commitChanges();
        //secondTreeView.commitChanges();
    }

                }

                function insertBefore(destinationNode, sourceNode)
                {
                    var destinationParent = destinationNode.get_parent();
                    var index = destinationParent.get_nodes().indexOf(destinationNode);
                    destinationParent.get_nodes().insert(index, sourceNode);
                }

                function insertAfter(destinationNode, sourceNode)
                {
                    var destinationParent = destinationNode.get_parent();
                    var index = destinationParent.get_nodes().indexOf(destinationNode);
                    destinationParent.get_nodes().insert(index+1, sourceNode);
                }


                function isValidDrop(sender, args)
                {

                    var tree = $find('trvOne');
                    var sourceNode = args.get_sourceNode();
                    var destinationNode = args.get_destNode();

                    var sourceNodeLevel;
                    var destinationNodeLevel;
                    sourceNodeLevel=getNodeLevel(sourceNode);
                    destinationNodeLevel=getNodeLevel(destinationNode);

                    if(sourceNodeLevel==destinationNodeLevel)
                        return true;
                    else
                        return false;
                    /*
                    if(!sourceNode.get_parent())
                    {
                        args.set_cancel(true);
                        tree._clearDrag();
                        return false;
                    }
                    if(sourceNode.get_parent() && !(sourceNode.get_parent().get_parent()))
                    {
                        args.set_cancel(true);
                        tree._clearDrag();
                        return false;
                    }
                    if(sourceNode.get_parent() && sourceNode.get_parent().get_parent() && !(sourceNode.get_parent().get_parent().get_parent()))
                    {
                        args.set_cancel(true);
                        tree._clearDrag();
                        return false;
                    }
                    */

                }


                function getNodeLevel(node)
                {
                    var FirstParent;
                    var SecondParent;
                    var ThirdParent;

                    var Level;

                    FirstParent=node.get_parent();
                    if(FirstParent)
                        SecondParent=FirstParent.get_parent();
                    if(SecondParent)
                        ThirdParent=SecondParent.get_parent();

                    if(ThirdParent)
                        Level=3;
                    else if(SecondParent)
                        Level=2;
                    else if(FirstParent)
                        Level=1;


                    return Level;

                }

                function dropOnHtmlElement(args)
                {
                    var target = args.get_htmlElement();

                    if (target.tagName == "SELECT" && target.id=='lstShortCut')
                    {

                        if(getNodeLevel(args.get_sourceNode())!=3)
                        {
                            args.set_cancel(true);
                            return;
                        }

                        target.style.cursor = "default";
                        //target.value = args.get_sourceNode().get_text();

                        var sourceNodeValue=args.get_sourceNode().get_value();
                        for(var i=0;i<target.options.length;i++)
                        {
                            if(target.options[i].value==sourceNodeValue)
                            {
                                args.set_cancel(true);
                                return true;
                            }
                        }

                        var newnewOpt = new Option( args.get_sourceNode().get_text(), args.get_sourceNode().get_value(), true, false);
                        target.options[target.options.length] = newOpt;

                        args.set_cancel(true);
                        return true;
                    }
                }





    </script>


<radT:RadAjaxManager ID="RadAjaxManager1" runat="server">
                                                    <AjaxSettings>
                                                            <radT:AjaxSetting AjaxControlID="trvOne">
                                                                <UpdatedControls>
                                                                    <radT:AjaxUpdatedControl ControlID="trvOne" />
                                                                </UpdatedControls>
                                                            </radT:AjaxSetting>
                                                        </AjaxSettings>
                                                    </radT:RadAjaxManager>
                                        <radT:RadTreeView ID="trvOne" runat="server"
                                            EnableViewState="true" SingleExpandPath="true" EnableDragAndDrop="true" OnClientNodeDropping="onNodeDropping"   Height="350px">