The amount of the payment as specified by you on DoDirectPaymentRequest.
Inheritance: AbstractResponseType
        private void setKeyResponseObjects(PayPalAPIInterfaceServiceService service, DoDirectPaymentResponseType response)
        {
            HttpContext CurrContext = HttpContext.Current;
            CurrContext.Items.Add("Response_apiName", "DoDirectPayment");
            CurrContext.Items.Add("Response_redirectURL", null);
            CurrContext.Items.Add("Response_requestPayload", service.getLastRequest());
            CurrContext.Items.Add("Response_responsePayload", service.getLastResponse());

            Dictionary<string, string> responseParams = new Dictionary<string, string>();
            responseParams.Add("Correlation Id", response.CorrelationID);
            responseParams.Add("API Result", response.Ack.ToString());

            if (response.Ack.Equals(AckCodeType.FAILURE) ||
                (response.Errors != null && response.Errors.Count > 0))
            {
                CurrContext.Items.Add("Response_error", response.Errors);
            }
            else
            {
                CurrContext.Items.Add("Response_error", null);
                responseParams.Add("Transaction Id", response.TransactionID);
                responseParams.Add("Payment status", response.PaymentStatus.ToString());
                if(response.PendingReason != null) {
                    responseParams.Add("Pending reason", response.PendingReason.ToString());
                }
            }
            CurrContext.Items.Add("Response_keyResponseObject", responseParams);
            Server.Transfer("../APIResponse.aspx");
        }
    // # DoDirectPaymentAPIOperation
    // The MassPay API operation makes a payment to one or more PayPal account holders.
    public DoDirectPaymentResponseType DoDirectPaymentAPIOperation()
    {
        // Create the DoDirectPaymentResponseType object
        DoDirectPaymentResponseType responseDoDirectPaymentResponseType = new DoDirectPaymentResponseType();

        try
        {
            // Create the DoDirectPaymentReq object
            DoDirectPaymentReq doDirectPayment = new DoDirectPaymentReq();
            DoDirectPaymentRequestDetailsType doDirectPaymentRequestDetails = new DoDirectPaymentRequestDetailsType();

            // Information about the credit card to be charged.
            CreditCardDetailsType creditCard = new CreditCardDetailsType();

            // Type of credit card. For UK, only Maestro, MasterCard, Discover, and
            // Visa are allowable. For Canada, only MasterCard and Visa are
            // allowable and Interac debit cards are not supported. It is one of the
            // following values:
            //
            // * Visa
            // * MasterCard
            // * Discover
            // * Amex
            // * Solo
            // * Switch
            // * Maestro: See note.
            // `Note:
            // If the credit card type is Maestro, you must set currencyId to GBP.
            // In addition, you must specify either StartMonth and StartYear or
            // IssueNumber.`
            creditCard.CreditCardType = CreditCardTypeType.VISA;

            // Credit Card number
            creditCard.CreditCardNumber = "4770461107194023";

            // ExpiryMonth of credit card
            creditCard.ExpMonth = Convert.ToInt32("12");

            // Expiry Year of credit card
            creditCard.ExpYear = Convert.ToInt32("2021");

            //Details about the owner of the credit card.
            PayerInfoType cardOwner = new PayerInfoType();

            // Email address of buyer.
            cardOwner.Payer = "*****@*****.**";
            creditCard.CardOwner = cardOwner;

            doDirectPaymentRequestDetails.CreditCard = creditCard;

            // Information about the payment
            PaymentDetailsType paymentDetails = new PaymentDetailsType();

            // IPN URL
            // * PayPal Instant Payment Notification is a call back system that is initiated when a transaction is completed        
            // * The transaction related IPN variables will be received on the call back URL specified in the request       
            // * The IPN variables have to be sent back to the PayPal system for validation, upon validation PayPal will send a response string "VERIFIED" or "INVALID"     
            // * PayPal would continuously resend IPN if a wrong IPN is sent        
            paymentDetails.NotifyURL = "http://IPNhost";

            // Total cost of the transaction to the buyer. If shipping cost and tax
            // charges are known, include them in this value. If not, this value
            // should be the current sub-total of the order.
            //
            // If the transaction includes one or more one-time purchases, this field must be equal to
            // the sum of the purchases. Set this field to 0 if the transaction does
            // not include a one-time purchase such as when you set up a billing
            // agreement for a recurring payment that is not immediately charged.
            // When the field is set to 0, purchase-specific fields are ignored.
            //
            // * `Currency Code` - You must set the currencyID attribute to one of the
            // 3-character currency codes for any of the supported PayPal
            // currencies.
            // * `Amount`
            BasicAmountType orderTotal = new BasicAmountType(CurrencyCodeType.USD, "4.00");
            paymentDetails.OrderTotal = orderTotal;
            doDirectPaymentRequestDetails.PaymentDetails = paymentDetails;

            // IP address of the buyer's browser.
            // `Note:
            // PayPal records this IP addresses as a means to detect possible fraud.`
            doDirectPaymentRequestDetails.IPAddress = "127.0.0.1";

            DoDirectPaymentRequestType doDirectPaymentRequest = new DoDirectPaymentRequestType(doDirectPaymentRequestDetails);
            doDirectPayment.DoDirectPaymentRequest = doDirectPaymentRequest;

            // Create the service wrapper object to make the API call
            PayPalAPIInterfaceServiceService service = new PayPalAPIInterfaceServiceService();

            // # API call
            // Invoke the DoDirectPayment method in service wrapper object
            responseDoDirectPaymentResponseType = service.DoDirectPayment(doDirectPayment);

            if (responseDoDirectPaymentResponseType != null)
            {
                // Response envelope acknowledgement
                string acknowledgement = "DoDirectPayment API Operation - ";
                acknowledgement += responseDoDirectPaymentResponseType.Ack.ToString();
                logger.Info(acknowledgement + "\n");
                Console.WriteLine(acknowledgement + "\n");

                // # Success values
                if (responseDoDirectPaymentResponseType.Ack.ToString().Trim().ToUpper().Equals("SUCCESS"))
                {
                    // Unique identifier of the transaction
                    logger.Info("Transaction ID : " + responseDoDirectPaymentResponseType.TransactionID + "\n");
                    Console.WriteLine("Transaction ID : " + responseDoDirectPaymentResponseType.TransactionID + "\n");

                }
                // # Error Values
                else
                {
                    List<ErrorType> errorMessages = responseDoDirectPaymentResponseType.Errors;
                    foreach (ErrorType error in errorMessages)
                    {
                        logger.Debug("API Error Message : " + error.LongMessage);
                        Console.WriteLine("API Error Message : " + error.LongMessage + "\n");
                    }
                }
            }
        }
        // # Exception log    
        catch (System.Exception ex)
        {
            // Log the exception message       
            logger.Debug("Error Message : " + ex.Message);
            Console.WriteLine("Error Message : " + ex.Message);
        }
        return responseDoDirectPaymentResponseType;
    }