PayuMoney返回无效的交易。请在成功功能中再试一次

Question

我在laravel 5.5上整合了PayuMoney。在payumoeny仪表板面板上支付成功，但是当成功功能返回时，＆＃34; PayuMomeny返回无效交易。请再试一次＆＃34;。

成功函数

public function payumoneyPaymentSuccess(Request $request)
    {
        $status         = $request->status;
        $firstname      = $request->firstname;
        $amount         = $request->amount;
        $txnid          = $request->txnid;
        $posted_hash    = $request->hash;
        $key            = $request->key;
        $productinfo    = $request->productinfo;
        $email          = $request->email;

        /*get salt*/
        $payumoneySetting = parent::getPaymentSetting();
        $payumoney = json_decode($payumoneySetting['PayUMoney'],true);
        $MERCHANT_KEY   = $payumoney['Merchant_Key'];
        $SALT           = $payumoney['Merchant_Salt'];
        $salt           = $SALT;
       //salt value is correct here

        // Salt should be same Post Request
        If (isset($_POST["additionalCharges"])) {
            $additionalCharges=$_POST["additionalCharges"];
            $retHashSeq = $additionalCharges.'|'.$salt.'|'.$status.'|||||||||||'.$email.'|'.$firstname.'|'.$productinfo.'|'.$amount.'|'.$txnid.'|'.$key;
        } else {
            $retHashSeq = $salt.'|'.$status.'|||||||||||'.$email.'|'.$firstname.'|'.$productinfo.'|'.$amount.'|'.$txnid.'|'.$key;
        }
        $hash = hash("sha512", $retHashSeq);
        if ($hash != $posted_hash) {
            echo "Invalid Transaction. Please try again";
        } else {
            echo "<h3>Thank You. Your order status is ". $status .".</h3>";
            echo "<h4>Your Transaction ID for this transaction is ".$txnid.".</h4>";
            echo "<h4>We have received a payment of Rs. " . $amount . ". Your order will soon be shipped.</h4>";
        }   

    }