Hi I have been trying to create payment module for EPIServer Commerce for DPS (Payment Express). I have been following other's example on creating module. I have been getting "Failed to process payment." after clicking next on payment page from the shopping cart. I am usinig EPIServer Commerce SP1. Product Version: 5.2 (build: 628) 

I am using Wine Sample shopping template.  I have included a bit code that i think is failing me.

I have hardcoded the values for purpose of testing. Any advice on this would be great. 

 public class PxPost : AbstractPaymentGateway
    {
        public static readonly string UserNameParameter = "";
        public static readonly string PasswordParameter = "";

        public static readonly string URL = "https://sec.paymetexpress.com/pxpost.aspx";
        public static readonly string TransactionType = "Purchase";
        public static readonly string Currency = "NZD";
        public override bool ProcessPayment(Payment payment, ref string message)
        {
          
            string PxPostUserName;
            string PxPostPassword;
            string PxPostURL;
            string TxnType;
            string Curr;
            if (!Settings.ContainsKey(UserNameParameter) ||
            !Settings.ContainsKey(PasswordParameter) ||
            !Settings.ContainsKey(URL) ||
            !Settings.ContainsKey(TransactionType)||
            !Settings.ContainsKey(Currency))
            {
                throw new Exception("PxPost is not configured yet");
            }

            PxPostUserName = Settings[UserNameParameter].ToString();
            PxPostPassword = Settings[PasswordParameter].ToString();
            PxPostURL = Settings[URL].ToString();
            TxnType = Settings[TransactionType].ToString();
            Curr = Settings[Currency].ToString();

            CreditCardPayment info =(CreditCardPayment) payment;

            StringWriter sw = new StringWriter();
            XmlTextWriter xtw = new XmlTextWriter(sw);
            xtw.WriteStartElement("Txn");
            xtw.WriteElementString("PostUsername", PxPostUserName);
            xtw.WriteElementString("PostPassword", PxPostPassword);
            xtw.WriteElementString("CardHolderName", info.CustomerName);
            xtw.WriteElementString("CardNumber", info.CreditCardNumber);
            xtw.WriteElementString("Amount", info.Amount.ToString("#.##"));
            xtw.WriteElementString("DateExpiry", info.ExpirationMonth < 10 ? "0" + info.ExpirationMonth.ToString() + info.ExpirationYear.ToString() : info.ExpirationMonth.ToString()+ info.ExpirationYear.ToString());
            xtw.WriteElementString("Cvc2", info.CreditCardSecurityCode);
            xtw.WriteElementString("InputCurrency", Curr);
            xtw.WriteElementString("TxnType", TxnType);
        // xtw.WriteElementString("TxnId", "");
    //       xtw.WriteElementString("MerchantReference", txtMerchantRef.Text);
    //      xtw.WriteElementString("TxnData1", txtTxnData1.Text);
        //    xtw.WriteElementString("TxnData2", txtTxnData2.Text);
        //   xtw.WriteElementString("TxnData3", txtTxnData3.Text);
            xtw.WriteEndElement();
            xtw.Close();
        // File.WriteAllText(path, sw.ToString(), Encoding.UTF8);
            //Send the Xml message to PXPost
         

                WebRequest wrq = WebRequest.Create(PxPostURL);
                wrq.Method = "POST";
                wrq.ContentType = "application/x-www-form-urlencoded";

                byte[] b = Encoding.ASCII.GetBytes(sw.ToString());
                wrq.ContentLength = b.Length;

                Stream s = wrq.GetRequestStream();
                s.Write(b, 0, b.Length);
                s.Close();

                WebResponse wrs = wrq.GetResponse();
           
            if (wrs != null)
            {
                StreamReader sr = new StreamReader(wrs.GetResponseStream());
                XmlDocument xd = new XmlDocument();
                xd.LoadXml(sr.ReadToEnd().Trim());

                info.TransactionID = xd.SelectSingleNode("/Txn/Transaction/AuthCode").InnerText;
                info.AcceptChanges();
            }
    
            message = "Payment Was successful";
            return true;

          
        }