I am having NullReferenceException

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data.SqlClient;

using System.Configuration;

using System.Data;

public partial class Currency : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

string senderNum;

string receiverNumber;

string reg;

senderNum = Request.QueryString.Get("sender");

receiverNumber = Request.QueryString.Get("receiver");

reg = Request.QueryString.Get("msg");

SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["rateD"].ConnectionString);

char[] splitchar = { ' ' };

if (reg == null == false)

{

string[] regis = reg.Split(splitchar);

string username;

string password;

//bool readerHasRows = false;

username = regis[0].ToString();

password = regis[1].ToString();

conn.Open();

SqlCommand cmd = new SqlCommand("SELECT Username FROM tblreg WHERE Username = @Username", conn);

cmd.Parameters.AddWithValue("@username", username);

SqlDataAdapter da = new SqlDataAdapter(cmd);

System.Data.DataTable dt = new DataTable();

da.Fill(dt);

if (dt.Rows.Count > 0)

{

//Try

Response.Redirect("http://localhost:9333/CurrencyConvertorOzeki?login=admin&password=abc123&action=sendMessage&messagetype=SMS:TEXT&recepient=" + senderNum + "&messageData= User already registered, Please register again");

}

else

{

SqlCommand cmd4 = new SqlCommand("INSERT INTO tblreg VALUES(@username,@password)", conn);

cmd4.Parameters.AddWithValue("@username", username);

cmd4.Parameters.AddWithValue("@password", password);

cmd4.ExecuteNonQuery();

Response.Redirect("http://localhost:9333/CurrencyConvertorOzeki?login=admin&password=abc123&action=sendMessage&messagetype=SMS:TEXT&recepient=" + senderNum + "&messageData= user succesfully registered");

}

}

else

{

string[] con = reg.Split(splitchar);

string username;

double value;

string count1;

string count2;

username = con[0].ToString();

value = double.Parse(con[1]);

count1 = con[2].ToString();

count2 = con[3].ToString();

conn.Open();

SqlCommand cmd5 = new SqlCommand("SELECT Username FROM tblreg WHERE Username = @Username", conn);

cmd5.Parameters.AddWithValue("@username", username);

SqlDataAdapter da1 = new SqlDataAdapter(cmd5);

System.Data.DataTable dt1 = new DataTable();

da1.Fill(dt1);

if (dt1.Rows.Count > 0)

{

conn.Open();

SqlCommand cmd6 = new SqlCommand("SELECT CountryCode FROM tblCountry WHERE CountryCode = @CountryCode1 AND CountryCode= @CountryCode2", conn);

cmd6.Parameters.AddWithValue("@CountryCode1", count1);

cmd6.Parameters.AddWithValue("@CountryCode2", count2);

SqlDataAdapter dac = new SqlDataAdapter(cmd6);

System.Data.DataTable dtc = new DataTable();

dac.Fill(dtc);

if (dtc.Rows.Count > 0)

{

net.webservicex.www.CurrencyConvertor conver = new net.webservicex.www.CurrencyConvertor();

net.webservicex.www.Currency From = (net.webservicex.www.Currency)Enum.Parse(typeof(net.webservicex.www.Currency), count1.ToString(), true);

net.webservicex.www.Currency To = (net.webservicex.www.Currency)Enum.Parse(typeof(net.webservicex.www.Currency), count2.ToString(), true);

double d = conver.ConversionRate(From, To);// web service method to call for conversion currency rate

String message = count1 + " To " + count2 + " : " + (d * Convert.ToDouble(value)).ToString();

Response.Redirect("http://localhost:9333/CurrencyConvertorOzeki?login=admin&password=abc123&action=sendMessage&messagetype=SMS:TEXT&recepient=" + senderNum + "&messageData=" + message + "");

}

}

else

{

Response.Redirect("http://localhost:9333/CurrencyConvertorOzeki?login=admin&password=abc123&action=sendMessage&messagetype=SMS:TEXT&recepient=" + senderNum + "&messageData= Please first register to get access to the service");

}

}

}

}