PHP GET parameter

Hello Team,

kindly advise why the parameter encrypted payload is blank when using GET? I am trying to set the field from URL.

$appID = $_GET['appID'];
$merTradeNo = $_GET['merTradeNo'];
$payload = $_GET['$encryptedPayload'];
$paymentType = $_GET['paymentType'];a
$sign = $_GET['sign'];

echo "APPID: " . $appID  . "<br>";
echo "MerchantTradeNo: " . $merTradeNo  . "<br>";
echo "PaymentType: " . $paymentType  . "<br>";
echo "Encrypted Payload: " . $payload  . "<br>";
echo "Signature: " . $sign  . "<br>";

https://snipboard.io/M5rP2X.jpg

This field is required for payment gateway authentication.

Thanks,

Roshan