Not able to use asp controls on code behind.

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C#

Hello everyone,
I am using a delgate object in my Web Application, in which I have to show some data in a control placed on the design page. I am not able to access any control of the .aspx page on my code behind as it shows exception that "use new keyword to initialize...." etc. I am not able to understand that why is this happening. Any if there is any solid reason for this to happen, then plz let me know that how could I show this record in a textbox or label. The line which is catching the exception is shown with a "//" below :

private void SSLCertificate()
{
    var servername = "www.xyz.com";

    Response.Write("\n\nFetching SSL cert for {0}\n" + servername);
    TcpClient client = new TcpClient(servername, 443);
    SslStream sslStream = new SslStream(client.GetStream(), false, callback, null);

    try
    {
        sslStream.AuthenticateAsClient(servername);
    }
    catch (AuthenticationException ex)
    {
       Response.Write("Exception: {0}"+ ex.Message);
        if (ex.InnerException != null)
        {
            Response.Write("Inner exception: {0}"+ ex.InnerException.Message);
        }
        Response.Write("Authentication failed - closing the connection.");
    }
    client.Close();
   }

static RemoteCertificateValidationCallback callback = delegate(object sender, X509Certificate cert, X509Chain chain, SslPolicyErrors sslError)
{
    SSLCert objSSLCert = new SSLCert();
     X509Certificate2 x509  = new X509Certificate2(cert);

    string str = x509.Subject;

    objSSLCert.txtDisplay.Text = "\n" + x509.Issuer.ToString(); //This line throwing error as null reference exception for textbox.

    if (sslError != SslPolicyErrors.None)
    {
        LogError();
    }

    return false;
};

[System.NullReferenceException] = {"Object reference not set to an instance of an object."}, This is the actual exception caught, and "use the "new" keyword to create an object instance.", is showing under the troubleshooting tips in exception box. Which gives an idea like I am trying to use an object without instantiating it, the object which is referred is textbox (I am sure for that). I want to know that how I use any asp control (textbox or label) for showing my record.

Thanks and Regards
Anurag