Script error in retrieving tree node text

Question

I got a script error when given to display the ASP.net TreeView node text as "alert(event.originalTarget.text)". The error is shown as "originalTarget.text is null or not an object".

$(document).ready(function() {
        $(".treeNode").draggable({helper:'clone'});
        $("#<%=TreeView1.ClientID %>").droppable({
            drop: function(event, ui) {
                alert(event.originalTarget.text);
            }
        });
    });

And sometimes I get error as The property does not support, when I use the methods like

tree.getTreeNode(tree.selectedNodeIndex);

Here "getTreeNode" and "selectedNodeIndex" does not work for me !