ถามเรื่อง listbox 2 ชั้น ให้สามารถรับบน firefox ได้ คับ

<script type=text/javascript >
 var arrItems = new Array();
 var arrItemsGrp = new Array();
 var arrItemValue = new Array();
 var arrItems2 = new Array();
 var arrItemsGrp2 = new Array();
 var arrItemValue2 = new Array();
<?
$objConnect = mysql_connect("localhost","root","1234") or die("Error Connect to Database");
$objDB = mysql_select_db("projectdb");
$sql11= "select * from subside"; 
mysql_query("SET NAMES UTF8");
$result11=mysql_query($sql11);
  while($row11=mysql_fetch_row($result11)) {
$x=$x+1;
echo "x=".$x.";";
$aaa=$row11[2];
$tbn=$row11[1];
$tbi=$row11[0];
echo "a=".$aaa.";";
echo "b='".$tbn."';";
echo "c=".$tbi.";";

 ?> 
arrItems2[x]=b;arrItemsGrp2[x]=a;arrItemValue2[x]=c;
<? } 
 ?>
function selectChange(control, controlToPopulate, ItemArray, GroupArray){
    var myEle ;
    var x ;
    for (var q=controlToPopulate.options.length;q>=0;q--) controlToPopulate.options[q]=null;
    myEle = document.createElement("option") ;
    myEle.value = " ";
    myEle.text = " -- เลือกประเภท -- " ;
    controlToPopulate.add(myEle) ;
    for ( x = 0 ; x < ItemArray.length  ; x++ )
   {
     if ( GroupArray[x] == control.value )
    {
      myEle = document.createElement("option") ;
      myEle.value = arrItemValue[x];
      myEle.text = ItemArray[x] ;
      controlToPopulate.add(myEle) ;
    }
   }
  controlToPopulate.focus();
 }


 function selectChange2(control2, controlToPopulate2, ItemArray2, GroupArray2){
    var myEle ;
    var x ;
    for (var q=controlToPopulate2.options.length;q>=0;q--) controlToPopulate2.options[q]=null;
    myEle = document.createElement("option") ;
    myEle.value = " ";
    myEle.text = " -- เลือกด้าน -- " ;
    controlToPopulate2.add(myEle) ;
    for ( x = 0 ; x < ItemArray2.length  ; x++ )
   {
     if ( GroupArray2[x] == control2.value )
    {
      myEle = document.createElement("option") ;
      myEle.value = arrItemValue2[x];
      myEle.text = ItemArray2[x] ;
      controlToPopulate2.add(myEle) ;
    }
   }
  controlToPopulate2.focus();
 }
</script>

<tr>
            <td  align="right" bgcolor="#00CCCC">ด้านหลัก&nbsp;&nbsp;&nbsp;</td>
            <td align="left" bgcolor="#00CCCC">
			<select name="side" id="side" size="1"class="fieldselect" onChange='selectChange2(this, form1.subside, arrItems2, arrItemsGrp2);document.getElementById("h_side").value=document.getElementById("side").options[document.getElementById("side").selectedIndex].text;'>
   <?
     $sql1= "select * from side ";   
	 mysql_query("SET NAMES UTF8");
     $result1=mysql_query($sql1);
	
  	while($row1=mysql_fetch_row($result1)) 
  	{
     echo"<option value=".$row1[0].">".$row1[1]."</option>";
	} 
   ?>
            </select>
			</td>
          </tr>
          <tr>
            <td align="right" bgcolor="#00CCFF">ด้านย่อย&nbsp;&nbsp;&nbsp;</td>
            <td align="left" bgcolor="#00CCFF">
			<select name="subside" size="1" class="fieldselect" id="subside" style="width: 180px;" onChange='document.getElementById("h_subside").value=document.getElementById("subside").options[document.getElementById("subside").selectedIndex].text;'>
            </select>
			</td>