Getting request was not allowed this time

Hi

I am trying following code in asp.net core and getting error in message

request was not allowed this time

string order_id = "Test" + DateTime.Now.ToString("yyyyMMddhhmmss");
string store_id = "MyStoreID";
string api_token = "MyApiToken";
string amount = "5.00";
string pan = "4242424242424242";
string expdate = "1901"; //YYMM format
string crypt = "7";
string processing_country_code = "CA";
bool status_check = false;

CofInfo cof = new CofInfo();
cof.SetPaymentIndicator("U");
cof.SetPaymentInformation("2");
cof.SetIssuerId("168451306048014");

Purchase purchase = new Purchase();
purchase.SetOrderId(order_id);
purchase.SetAmount(amount);
purchase.SetPan(pan);
purchase.SetExpDate("2011");
purchase.SetCryptType(crypt);
purchase.SetDynamicDescriptor("2134565");
//purchase.SetWalletIndicator(""); //Refer to documentation for details
purchase.SetCofInfo(cof);

//purchase.SetCmId("8nAK8712sGaAkls56"); //set only for usage with Offlinx - Unique max 50 alphanumeric characters transaction id generated by merchant

HttpsPostRequest mpgReq = new HttpsPostRequest();
mpgReq.SetProcCountryCode(processing_country_code);
mpgReq.SetTestMode(true); //false or comment out this line for production transactions
mpgReq.SetStoreId(store_id);
mpgReq.SetApiToken(api_token);
mpgReq.SetTransaction(purchase);
mpgReq.SetStatusCheck(status_check);
mpgReq.Send();

try
{
Receipt receipt = mpgReq.GetReceipt();
var result = "";
result = "CardType = " + receipt.GetCardType();
result = "TransAmount = " + receipt.GetTransAmount();
result = "TxnNumber = " + receipt.GetTxnNumber();
result = "ReceiptId = " + receipt.GetReceiptId();
result = "TransType = " + receipt.GetTransType();
result = "ReferenceNum = " + receipt.GetReferenceNum();
result = "ResponseCode = " + receipt.GetResponseCode();
result = "ISO = " + receipt.GetISO();
result = "BankTotals = " + receipt.GetBankTotals();
result = "Message = " + receipt.GetMessage();
result = "AuthCode = " + receipt.GetAuthCode();
result = "Complete = " + receipt.GetComplete();
result = "TransDate = " + receipt.GetTransDate();
result = "TransTime = " + receipt.GetTransTime();
result = "Ticket = " + receipt.GetTicket();
result = "TimedOut = " + receipt.GetTimedOut();
result = "IsVisaDebit = " + receipt.GetIsVisaDebit();
result = "HostId = " + receipt.GetHostId();
result = "IssuerId = " + receipt.GetIssuerId();
//Console.ReadLine();
}
catch (Exception e)
{

//Console.WriteLine(e);
}