สอบถามหน่อยครับ พอดีทำตะกร้าสินค้า ค่าราคารวมไม่คำนวณ

<script type="text/javascript">
function doCalSum(row, amt, Price){
var Sum;
Sum = parseInt(amt) * parseFloat(Price);
document.getElementById("hdnSum" + row).value = Sum.toFixed(2);
document.getElementById("spnSum" + row).innerHTML = Sum.toFixed(2);
doCalTotal()
$sum=Sum;
$result = $sum;
return $result;
}

function doCalTotal(){
var row = document.getElementById("hdnCount").value;
var Total = 0;
for(i=0;i<=row;i++){
Total += parseFloat(document.getElementById("hdnSum" + i).value);
}
document.getElementById("spnTotal").innerHTML = Total.toFixed(2);
}

function digitsOnly(obj){
var regExp = /[0-9]$/;
if(!regExp.test(obj.value)){
obj.value = obj.value.substring(0, obj.value.length -1);
return false;
}
}
</script>

<?php
if(!$_SESSION["username"]){
    	echo "<script>alert('กรุณาเข้าสู่ระบบ');</script>";
		echo "<script language=javascript>window.location = 'index.php';</script>";
}
if($_SESSION['s_product_id'] == 0){
echo "<br><div class='alert alert-danger' align=center>ไม่มีสินค้าในตะกร้า</div>";
}else if ($_SESSION['s_product_id'] > 1){
echo "<meta charset='utf-8'>";
?>
<table class="table  table-hover" style="border:5px double #CCC; ">
	<tr class="info">
		<th><center><h3><b>สินค้าในตะกร้า</b></h3><center></th>
	</tr>
</table>
<?php
$cnt = count($_SESSION['s_product_id']);
?>

<div class="panel-body">
<table class="table  table-bordered " id="dataTables-example">
<form action='index.php?modules=basket&file=calculate' method='post'>
	<tr class="active">
		<th>ลบ</th>
		<th>รหัสสินค้า</th>
		<th>ชื่อสินค้า</th>
		<th>ราคา</th>
		<th>จำนวน</th>
		<th>ราคารวม</th>
	</tr>
<?php

if(empty($_SESSION[ems])){
	$_SESSION[ems] = 150;
}

for($i=0;$i<$cnt;$i++){
$total=($_SESSION['s_p_Price'][$i] * $_SESSION['s_amount'][$i]);
?>
<tr>
<td><center><input type='checkbox' value='<?php echo $_SESSION['s_product_id'][$i]; ?>' name='del_id[]'></center></td>
<td><?php echo $_SESSION['s_product_id'][$i]; ?></td>  <!--รหัสสินค้า-->
<td><?php echo $_SESSION['s_p_name'][$i]; ?></td>   <!--ชื่อสินค้า-->
<td><?php echo $_SESSION['s_p_Price'][$i]; ?></td> 	<!--ราคาสินค้า-->
<td><input type='textbox' name='amount[]' size='5' value='<?php echo $_SESSION['s_amount'][$i]; ?>' onkeyup="digitsOnly(this);doCalSum('<?=$i?>', this.value,' <?=$_SESSION['s_p_Price'][$i]?>')"></td> <!--จำนวนสินค้า-->
<td align=right><span name="spnSum" id="spnSum<?=$i?>"><?php $sum = ($_SESSION['s_amount'][$i]*$_SESSION['s_p_Price'][$i]); ?></span> <!--ราคารวมสินค้า-->
<input type="hidden" name="hdnSum" id="hdnSum<?=$i?>" value="<?=$_SESSION['s_p_Price'][$i]?>" />

</tr>
<?php
}
?>
<tr>
<td colspan='5' align='right'><input type='checkbox' name='checkems' ".$_SESSION[chk]."> ส่งแบบ EMS </td><td align=right><?=$_SESSION[ems]?></td>
</tr>
<tr>
<td colspan="5" align="right">ราคารวมทั้งหมด</td>
<td align="right"><span name="spnTotal[]" id="spnTotal"></span><?=$Total?></td>
<input type="hidden" name="hdnCount" id="hdnCount">
</tr>
</table>
</form>
<?
}
?>