ทำไมเขียน code javascript แล้ว radio button ยังไม่ disable

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link href="main_style.css" rel="stylesheet" type="text/css">
<title>ตรวจสภาพรถ</title>
<? include "connect.php";?>
<script language="javascript">
function dis()
{ 
	var Rows = document.form1.count.value;
	for(i=1;i<=Rows;i++)
	{
		var jing1 = document.getElementById("jing"+i+"_1");		
		var jing2 = document.getElementById("jing"+i+"_2");
					
		var bill1 = document.getElementById("bill"+i+"_1");		
		var bill2 = document.getElementById("bill"+i+"_2");
			
		var sapab1 = document.getElementById("sapab"+i+"_1");		
		var sapab2 = document.getElementById("sapab"+i+"_2");	
		var sapab3 = document.getElementById("sapab"+i+"_3");
		
		var error = document.getElementById("error"+i+"");	
			
		//alert(Rows);
	 if(jing1.checked==true)
		   {
			sapab1.disabled=false;
			sapab2.disabled=false;
			sapab3.disabled=false;

		   }
			 
		  else if(jing2.checked==true)
		   {
			sapab1.disabled=true;
			sapab2.disabled=true;
			sapab3.disabled=true;
			
			sapab1.checked=false;
			sapab2.checked=false;	
			sapab3.checked=false;
		   }
	}//end for
}
</script>


<form action="save_estchkmotor.php" method="post" name="form1" OnSubmit="return fncSubmit(); " > 	
<table width="980px" class="three"  style="font-size:12px;font-family:Verdana, Geneva, sans-serif;" >
<tr bgcolor="#999999" height="30">
  <th width="91" rowspan="2">ลำดับ</th>
  <th width="300" rowspan="2">รายการ</th>
  <th colspan="2">ตามใบตรวจสภาพ--bill</th>
  <th colspan="2">ตามที่ตรวจจริง--jing</th>
  <th colspan="3">มี</th>
  <th width="85" rowspan="2">ผิดพลาด</th>
  <th width="85" rowspan="2">ของแต่ง</th>
</tr>
<tr bgcolor="#999999" height="30">
  <th width="102">มี--1</th>
  <th width="83">ไม่มี--2</th>
  <th width="102">มี--1</th>
  <th width="83">ไม่มี--2</th>
  <th width="102">ชำรุด</th>
  <th width="83">ใช้งานไม่ได้</th>
  <th width="85">ใช้ได้</th>
</tr>
<?
$i = 1;
$i = $i++;
while($objResult = mysql_fetch_array($query))
{
	$sp_id 		= $objResult["sp_id"];
	$sp_code 	  = $objResult["sp_code"];
	$sp_name 	  = $objResult["sp_name"];
	$brand_name   = $objResult["brand_name"];
	$class_name   = $objResult["class_name"];
	$brand_id     = $objResult["brand_id"];
	if($i%2==0)
	{
	$bg = "#FFFFFF";
	}
	else
	{
	$bg = "#eff3fa";
	}
?>
<tr align="center" height="25" bgcolor="<?=$bg;?>" onMouseOver="this.bgColor='#cedbef'" onMouseOut ="this.bgColor = '<?=$bg;?>'" >
    <td align="center"><?=$i++;?><input type="hidden" id="machine_id" name="machine_id" value="<?=$mID;?>"</td>
    <td align="left"><?=$sp_name;?><input name="sp_code[<?=$i?>]" type="hidden" value="<?=$sp_code;?>" /></td>
    <!--มี/ไม่มี ของใบตรวจสภาพ-->
    <td><input name="bill[<?=$i;?>]"   id="bill<?=$i;?>_1"   type="radio" value="1" onclick="dis()" /></td>
    <td><input name="bill[<?=$i;?>]"   id="bill<?=$i;?>_2"   type="radio" value="2" onclick="dis()" /></td>
    <!--มี/ไม่มี ตามที่ตรวจจริง-->
    <td><input name="jing[<?=$i;?>]"   id="jing<?=$i;?>_1"   type="radio" value="1" onclick="dis()" /></td>
    <td><input name="jing[<?=$i;?>]"   id="jing<?=$i;?>_2"   type="radio" value="2" onclick="dis()" /></td>
    <!-- ใช้ได้ ชำรุด ใช้ไม่ได้-->
    <td><input name="sapab[<?=$i;?>]"  id="sapab<?=$i;?>_1" type="radio" value="1" onclick="dis()" /></td>
    <td><input name="sapab[<?=$i;?>]"  id="sapab<?=$i;?>_2" type="radio" value="2" onclick="dis()" /></td>
    <td><input name="sapab[<?=$i;?>]"  id="sapab<?=$i;?>_3" type="radio" value="3" onclick="dis()" /></td>
    <!-- รายการผิดพลาด ชุดแต่ง-->
    <td><input name="error[<?=$i;?>]"  id="error<?=$i;?>_1"  type="checkbox" value="1" onclick="dis()" /></td>
    <td><input name="race[<?=$i;?>]"   id="race<?=$i;?>"   type="checkbox" value="1" onclick="dis()"/></td>
</tr>
<? } ?>
</table>
<button type="submit" id="bttn" name="bttn"><img src="image/save.png">บันทึก</button>
</div>
<input type="hidden" id="count" name="count" value="<?=$count;?>" />
</form>