ช่วยดูโค้ดให้หน่อยค่ะว่าทำไมเราคลิกเลือกชื่อใน list box อันที่สองแล้วทำไมไม่โชว์ชื่อที่เราเลือกให้เหนเลย

<?
				  $status=$_SESSION['status'];

                $id1=$_SESSION['id_a'];
			
				?>
  <p align="center">การให้คำปรึกษา</p>
  <table width="528" border="0" align="center">
    <tr>
      <th width="114" scope="col"><div align="right">หัวข้อเรื่อง:</div></th>
      <th colspan="2" scope="col"><div align="left">
        <input name="head" type="text" id="head" size="40" />
      </div></th>
    </tr>
    <tr>
      <td>&nbsp;</td>
      <td colspan="2">&nbsp;</td>
    </tr>
    <tr>
      <td><div align="center"><strong>รายละเอียด:</strong></div></td>
      <td colspan="2"><textarea name="detail" id="detail" cols="40" rows="5"></textarea></td>
    </tr>
    <tr>
      <td>&nbsp;</td>
      <td colspan="2">&nbsp;</td>
    </tr>

    <?php if ($row_t['status']=='1') { ?>
    <? //if (status=='1') { ?>
    <tr>
      <td height="27"><div align="center"><strong>หมุ่เรียน:</strong></div></td>
      <td width="154"><label>
        <select name="a" id="a" title="<?php echo $row_rs_class['name_class']; ?>" onChange = "ListRoom(this.value)"  >
          <?php
do {  
?>
          <option value="<?php echo $row_rs_class['name_class']?>"><?php echo $row_rs_class['name_class']?></option>
          <?php
} while ($row_rs_class = mysql_fetch_assoc($rs_class));
  $rows = mysql_num_rows($rs_class);
  if($rows > 0) {
      mysql_data_seek($rs_class, 0);
	  $row_rs_class = mysql_fetch_assoc($rs_class);
  }
?>
        </select>
      </label>
            <?php
do {  
?>

</td>
<option value="<?php echo $row_rs_class['name_class']?>"<?php if (!(strcmp($row_rs_class['name_class'], $row_a['class_']))) {echo "selected=\"selected\"";} ?>></option>
          <?php
} 
while ($row_rs_class = mysql_fetch_assoc($rs_class));
  $rows = mysql_num_rows($rs_class);
  if($rows > 0) {
      mysql_data_seek($rs_class, 0);
	  $row_rs_class = mysql_fetch_assoc($rs_class);
  }
?>
    </tr>
    <tr>
      <td><div align="center"><strong>ถึงนักศึกษาในที่ปรึกษา:</strong></div></td>
      <td colspan="2"><label>
      <select name="id_stu" id="id_stu" onChange = "ListRoom(this.value)"/>
       <option value="<?=$id_stu?>">
        <? if($id_stu){echo"$id";}else if(!$id_stu){echo"เลือก";}?>
        </option>
      </select>
      </label></td>
    </tr>
 <? } ?>
    <tr>
      <td>&nbsp;</td>
      <td><?php if ($row_t['status']=='0') { echo $row_teach['name_tech'];} ?></td>
    </tr> 
    <tr>
      <td>&nbsp;</td>
      <td colspan="2"><input type="submit" name="button" id="button" value="ส่งข้อมูล" /></td>
    </tr>
  </table>
  <br>
  <?
  /* ==========================================================================================*/
  ?>

  <script language="javascript" type="text/javascript">

 function setage()
 {
	 var selectList = document.frmselect("name");
		for (i=0;i<selectList.options.length;i++)
		{
			 selectList.removeChild(selectList.options.item(i));	
		}
		
  var index_name=document.frmselect.name.selectedIndex;
  
  
  
  document.frmselect.age.selectedIndex=index_name;
  
 }
  </script>
  </form>
<script> 
		function ListRoom(SelectValue)
		{
			form1.id_stu.length = 0

			//*** Insert null Default Value ***//
			var myOption = new Option('','')  
			form1.id_stu.options[form1.id_stu.length]= myOption
			
			<?
			$intRows = 0;
			$strSQL = "SELECT * FROM adv_data ";
			$objQuery = mysql_query($strSQL) or die ("Error Query [".$strSQL."]");
			$intRows = 0;
			while($objResult = mysql_fetch_array($objQuery))
			{
			$intRows++;
			?>
				x = <?=$intRows;?>;
				var mySubList = new Array();
				
				var strID = <?=$objResult["id"];?>;
				var strName = "<?=$objResult["fname"];?>";
				var strLastName = "<?=$objResult["lname"];?>";
				var status = "<?=$objResult["status"];?>";
				mySubList[x,0] = strID;
				mySubList[x,1] = strName;
				mySubList[x,2] = strLastName;
				mySubList[x,3] = status;
							
							
				if (mySubList[x,3] == 0){
					var myOption = new Option(mySubList[x,1], mySubList[x,2])  
					form1.id_stu.options[form1.id_stu.length]= myOption					
				}
			<?
			}
			?>																	
		}
		
</script>