Retrieving JSON Values - php

Question

I am working with a php payment api https://simplepay4u.com/developer.php
I have followed every step successfully but can't seem to get return values to generate a receipt after payment. I am stock not understanding the what the unotify page should be doing.
Here is my form which is posting properly:
$action = $_POST["action"];
$pid = $_POST["pid"];
$buyer = $_POST["buyer"];
$total = $_POST["total"];
$comments = $_POST["comments"];
$referer = $_POST["referer"];
$customid = $_POST["customid"];
$transaction_id = $_POST["customid"];
$val = #json_encode($_POST);
// For Loging $val can be used
if ($referer == "https://simplepay4u.com"
|| $referer == "https://www.simplepay4u.com"
|| "http://sandbox.simplepay4u.com/process.php") //1st level checking
{
if (!empty($transaction_id)) //2nd level checking
{
/*** Server side verification. Your server is communicating with Simplepay Server Internally**/
//$simplepay_url="https://simplepay4u.com/processverify.php"; // Live URL
$simplepay_url = "http://sandbox.simplepay4u.com/processverify.php";
$curldata["cmd"] = "_notify-validate";
foreach ($_REQUEST as $key => $value) {
if ($key != 'view' && $key != 'layout') {
$value = urlencode($value);
$curldata[$key] = $value;
}
}
$handle = curl_init();
curl_setopt($handle, CURLOPT_URL, $simplepay_url);
curl_setopt($handle, CURLOPT_POST, 1);
curl_setopt($handle, CURLOPT_POSTFIELDS, $curldata);
curl_setopt($handle, CURLOPT_SSL_VERIFYPEER, 0);
curl_setopt($handle, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($handle, CURLOPT_TIMEOUT, 90);
$result = curl_exec($handle);
curl_close($handle);
var_dump(json_decode($result));
enter code here
if ('VERIFIED' == $result) {
// IMPLEMENTATION CODE & aPPLICATION lOGIC WILL GO HER TO UPDATE THE ACCOUNT
}
}
}
I have set my ureturn page to carry the above script and tried var_dump(json_decode($result)), print_r($result) and echo $result; Just to see something but I get the result.
Can someone please tell me what to do to get my return values after posting my already working form?