How can I fix this error implementing CommWeb on my website? - php

Question

I am trying to implement CommWeb on my PHP site. It isn't working. I am getting following error message:
HTTP Status - 400
E5000: Required field vpc_AccessCode was not present in the request
How can I fix this? I haven't found anything helpful in the documentation.
Here is my code:
<?php
//Merchant Admin URL: https://migs.mastercard.com.au/ma/CBA
//Merchant ID: TEST
//Operator ID: Admin
//Password: d#test
// Access Code AEFTEST 1A22FTESTTEST
$session_id = 1;
$finalprice = 50;
$testarr = array(
"vpc_Amount" => $finalprice*100,//Final price should be multifly by 100
"vpc_AccessCode" => "AEFTEST",//Put your access code here
"vpc_Command"=> "pay",
"vpc_Locale"=> "en",
"vpc_MerchTxnRef"=> "CLI".$session_id, //This should be something unique number, i have used the session id for this
"vpc_Merchant"=> "TEST",//Add your merchant number here
"vpc_OrderInfo"=> "1A22FTESTTEST",//this also better to be a unique number
"vpc_ReturnURL"=> "http://localhost/test1/index.php/commweb/",//Add the return url here so you have to code here to capture whether the payment done successfully or not
"vpc_Version"=> "1");
ksort($testarr); // You have to ksort the arry to make it according to the order that it needs
$SECURE_SECRET = "d#test";//Add the secure secret you have get
$securehash = $SECURE_SECRET;
$url = "https://migs.mastercard.com.au/ma/CBA";
foreach ($testarr as $key => $value)
{
$securehash .= $value;
$url .= $key."=".urlencode($value)."&";
}
$securehash = md5($securehash);//Encoding
$url .= "vpc_SecureHash=".$securehash;
header("location:https://migs.mastercard.com.au/vpcpay?$url");
?>