Problem with DataBinder.saveAll

		binder = new DataBinder();
		list = new BindingListModelList(persons, false);
		listbox.setModel(list);
		
		listbox.setItemRenderer(new ListitemRenderer() {
			@Override
			public void render(Listitem item, Object data) throws Exception {
				Person person = (Person) data;
				binder.bindBean(item.getId(), person);
				
				Textbox name = new Textbox();
				name.setValue(person.getName());
				binder.addBinding(name, "value", item.getId() + ".name", null, null, "save", null, null, null, null);
				Listcell listcell = new Listcell();
				name.setParent(listcell);
				listcell.setParent(item);
				
				Textbox age = new Textbox();
				age.setValue(person.getAge());
				binder.addBinding(age, "value", item.getId() + ".age", null, null, "save", null, null, null, null);
                                //modify name to age

				listcell = new Listcell();
				age.setParent(listcell);
				listcell.setParent(item);
			}
		});
	}
	
	public void onClick$btn_save() {	
		binder.saveAll();	
	}
	
	public void onClick$btn_add() {				
		binder=new DataBinder();
		persons.add(new Person("Test3","3"));
		list.clear();
		list.addAll(persons);			
	}

package com.test.binding;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import org.zkoss.bind.annotation.AfterCompose;
import org.zkoss.bind.annotation.Command;
import org.zkoss.bind.annotation.ContextParam;
import org.zkoss.bind.annotation.ContextType;
import org.zkoss.zk.ui.Component;
import org.zkoss.zkplus.databind.AnnotateDataBinder;
import org.zkoss.zkplus.databind.Binding;
import org.zkoss.zkplus.databind.BindingListModelList;
import org.zkoss.zul.ListModel;
import org.zkoss.zul.ListModelList;
import org.zkoss.zul.Listcell;
import org.zkoss.zul.Listitem;
import org.zkoss.zul.ListitemRenderer;
import org.zkoss.zul.Textbox;

public class TestRenderer {

	ListModelList model = new ListModelList();
	private AnnotateDataBinder binder;

	@AfterCompose
	public void afterCompose(@ContextParam(ContextType.VIEW) Component view) {
		binder = new AnnotateDataBinder(view);
		List persons = new ArrayList();
		model.add(new Person("David", "Coverdale"));
		model.add(new Person("Doug", "Aldrich"));
		model.add(new Person("Reb", "Beach"));
		model.add(new Person("Michael", "Devin"));
		model.add(new Person("Brian", "Tichy"));

	}

	public void setModel(ListModelList model) {
		this.model = model;
	}

	public ListModel getModel() {

		return model;
	}

	// method for ZK 6
	public ListitemRenderer getItemRenderer() {
		ListitemRenderer _rowRenderer = null;
		if (_rowRenderer == null) {

			_rowRenderer = new ListitemRenderer() {
				public void render(final Listitem item, Object object, int index)
						throws Exception {
					final Person dataBean = (Person) object;

					binder.bindBean(item.getId(), dataBean);

					Listcell cell = new Listcell();
					Textbox name = new Textbox();
					name.setValue(dataBean.getFirstName());
					binder.addBinding(name, "value", item.getId()
							+ ".firstName", null, null, "save", null, null,
							null, null);
					cell.appendChild(name);
					cell.setParent(item);
					binder.bindBean(item.getId(), dataBean);
				}
			};
			binder.saveAll();
			binder.loadAll();
		}
		return _rowRenderer;
	}

	@Command
	public void onOK() {
		binder.loadAll();
		binder.saveAll(); // load Inputfields from Form, Constraints will be
							// performed
	}

	public class Person {
		private String firstName;
		private String lastName;

		public Person(String fn, String ln) {
			setFirstName(fn);
			setLastName(ln);
		}

		public String getFirstName() {
			return firstName;
		}

		public void setFirstName(String fn) {
			firstName = fn;
		}

		public String getLastName() {
			return lastName;
		}

		public void setLastName(String ln) {
			lastName = ln;
		}

	}

}

<zk>
  <window border="normal" title="hello" apply="org.zkoss.bind.BindComposer"
		viewModel="@id('vm') @init('com.test.binding.TestRenderer')" >
     <button label="ClickMe" id="retrieve"
						onClick="@command('onOK')">
					</button>
    <div height="800px">
      <listbox model="@load(vm.model)" itemRenderer="@load(vm.itemRenderer)" vflex="true" multiple="true"/>
    </div>
  </window>
</zk>

@AfterCompose
	public void afterCompose(@ContextParam(ContextType.VIEW) Component view) {
		binder = new AnnotateDataBinder(view);

@Init
public void init(
        @ContextParam(ContextType.BINDER) Binder binder) {
	this.binder = binder;
}