Databinding radiogroup problem

<?page title="Index" contentType="text/html;charset=UTF-8"?>
<?init class="org.zkoss.zkplus.databind.AnnotateDataBinderInit" ?>
<zk>
    <zscript>
    	boolean test = true;
    </zscript>
	<window id="testWin" title="Index" border="normal">
	    <vbox>
	    <radiogroup selectedItem="@{test, converter=webtests.binder.RadiogroupBooleanConverter}">
	    <radio label="Yes" value="true"/>
	    <radio label="No" value="false"/>
	    </radiogroup>
		<label id="hide" value="@{test}"/>
		</vbox>
	</window>
</zk>

package webtests.binder;

/* 

{{IS_NOTE
   Purpose:
          Description:
          History:
       Mon Mar 12 11:05:43     2007, Created by Henri
}}IS_NOTE

Copyright (C) 2007 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
}}IS_RIGHT
*/

import java.util.Iterator;

import org.zkoss.zk.ui.Component;
import org.zkoss.zkplus.databind.TypeConverter;
import org.zkoss.zul.Radio;
import org.zkoss.zul.Radiogroup;

/**
* Convert Radiogroup selected item to radio value and vice versa.
* modified for boolean
*
* zk's RadiogroupSelectedListItemConverter modified for boolean
* @author Henri
*/
public class RadiogroupBooleanConverter implements TypeConverter, java.io.Serializable {
        private static final long serialVersionUID = -7692059172828069699L;

   public Object coerceToUi(Object val, Component comp) { //load
       if (val != null && val instanceof Boolean) {
           Boolean bval = (Boolean) val;
           //iterate to find the selected radio via the value
           for (Iterator it = comp.getChildren().iterator(); it.hasNext();) {
               final Component child = (Component)it.next();
               if (child instanceof Radio) {
                   if (bval.toString().equalsIgnoreCase(((Radio)child).getValue())) {
                       return child;
                   }
               } else if (!(child instanceof Radiogroup)) { //skip nested radiogroup
                   //bug 2464484
                   final Object value = coerceToUi(val, child); //recursive
                   if (value != null) {
                       return value;
                   }
               }
           }
       }
       return null;
   }

   public Object coerceToBean(Object val, Component comp) { //save
               return val != null ? Boolean.parseBoolean(((Radio)val).getValue()) : null;
   }
}