Vaadin 7, treetable : not able to trigger addValueChangeListener on clickin

Hi All,

I am working on treetable and trying to use addValueChangeListener on clicking the tree node.
It works fine if we click on the empty space in the tree node but if we click on the text on tree node it will not trigger.

TreeTable ttable = new TreeTable("My TreeTable");
    		ttable.addContainerProperty("Name", String.class, null);
    		ttable.addContainerProperty("Number", Integer.class, null);

    		// Create the tree nodes and set the hierarchy
    		ttable.addItem(new Object[]{new Label("Menu"), null}, 0);
    		ttable.addItem(new Object[]{new Label("Beverages"), null}, 1);
    		ttable.setParent(1, 0);
    		ttable.addItem(new Object[]{new Label("Foods"), null}, 2);
    		ttable.setParent(2, 0);
    		ttable.addItem(new Object[]{new Label("Coffee"), 23}, 3);
    		ttable.addItem(new Object[]{new Label("Tea"), 42}, 4);
    		ttable.setParent(3, 1);
    		ttable.setParent(4, 1);
			ttable.addValueChangeListener(new ValueChangeListener() {
				public void valueChange(ValueChangeEvent event) {
					// TODO do something here

Here if we click on the “Menu” (which is a label) nothing happens but if we click on the empty space next to the text
it triggers the addValueChangeListener event. What shall i do to make it trigger the event when we click on the “Menu”?

PS: It is just an example code I wrote, Since i can not post the orignal code.

Thanks in advance.