getting error while debugging "There is no row at position 0."

try
{
    if (txtEmail.Text.Trim() != "")
    {
        MailMessage Msg = new MailMessage();
        // Sender e-mail address.
        Msg.From = new MailAddress("dkotagiri@technocratsdomain.com");
        // Recipient e-mail address.
        Msg.To.Add(txtEmail.Text);
        Msg.Subject = "Your Password Details";
        Msg.Body = "Hi, <br />Please check your Login Detailss<br /><br />Your Username: " + ds.Tables[0].Rows[0]["PrimaryEmail"] + "<br /><br />Your Password: " + ds.Tables[0].Rows[0]["Password"] + "<br /><br />";
        //Msg.Body = "hi";
        Msg.IsBodyHtml = true;
        // your remote SMTP server IP.
        SmtpClient smtp = new SmtpClient();
        smtp.Host = "66.203.144.99";
        smtp.Port = 25;
        smtp.Credentials = new System.Net.NetworkCredential("dkotagiri@technocratsdomain.com", "Microsoft123#");
        smtp.EnableSsl = true;
        ServicePointManager.ServerCertificateValidationCallback = delegate(object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) { return true; };
        smtp.Send(Msg);
        //Msg = null;
        lbltxt.Text = "Your Password Details Sent to your mail";
        // Clear the textbox valuess
        txtEmail.Text = "";
    }
    else
    {
        lbltxt.Text = "The Email you entered not exists.";
    }
}
catch (Exception ex)
{
}