function loadSubCategory(){
    var category_id=document.getElementById('category_id').options[document.getElementById('category_id').selectedIndex].value;
    xmlObjSubCategory = new XmlConnector(window.location.protocol + "//" + window.location.hostname +"/xml_load_sub.php?cat_id=" + category_id );
    xmlObjSubCategory.XMLReq.onreadystatechange = loadSubCategory_onDataLoad;
}
function loadSubCategory_onDataLoad(){
    if (xmlObjSubCategory.XMLReq.readyState == 4) {	
      if (xmlObjSubCategory.XMLReq.status  == 200) {				
          var rsSubcat = xmlObjSubCategory.XMLReq.responseXML.getElementsByTagName("subcat");
          document.getElementById('sub_cat_id').innerHTML = rsSubcat[0].childNodes[0].data ;    
      }
  }
}