WPF login example doesn't work

Question

As I stated before I put it in debug and get a row back from my sql statement.  The username gets loaded properly.  When I tried to load the textblock is when I get the error. 

Here is the code.  My table name is Users in my database.

using

System;

using

System.Collections.Generic;

using

System.Linq;

using

System.Text;

using

System.Windows;

using

System.Windows.Controls;

using

System.Windows.Data;

using

System.Windows.Documents;

using

System.Windows.Input;

using

System.Windows.Media;

using

System.Windows.Media.Imaging;

using

System.Windows.Navigation;

using

System.Windows.Shapes;

using

System.Data;

using

System.Data.SqlClient;

using

System.Text.RegularExpressions;

namespace

{

Login_WPF/// <summary>

/// Interaction logic for MainWindow.xaml

/// </summary>

public partial class Login : Window

{

{

InitializeComponent();

}

{

{

errormessage.Text =

textBoxEmail.Focus();

}

{

errormessage.Text =

textBoxEmail.Select(0, textBoxEmail.Text.Length);

textBoxEmail.Focus();

}

public Login()Registration registration = new Registration();Welcome welcome = new Welcome();private void button1_Click(object sender, RoutedEventArgs e)if (textBoxEmail.Text.Length == 0)"Enter an email.";else if (!Regex.IsMatch(textBoxEmail.Text, @"^[a-zA-Z][\w\.-]*[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$"))"Enter a valid email.";else

{

con.Open();

cmd.CommandType =

adapter.SelectCommand = cmd;

adapter.Fill(dataSet);

{

welcome.TextBlockName.Text = username;

string email = textBoxEmail.Text;string password = passwordBox1.Password;SqlConnection con = new SqlConnection(@"Data Source=.\sqlexpress;Initial Catalog=Customer;Integrated Security=True;Pooling=False");SqlCommand cmd = new SqlCommand("Select * from Users where Email='" + email + "' and Password='" + password + "'", con);CommandType.Text;SqlDataAdapter adapter = new SqlDataAdapter();DataSet dataSet = new DataSet();if (dataSet.Tables[0].Rows.Count > 0)string username = dataSet.Tables[0].Rows[0]["FirstName"].ToString() + " " + dataSet.Tables[0].Rows[0]["LastName"].ToString(); //Sending value from one form to another form.

welcome.Show();

Close();

}

else

{

errormessage.Text =

}

con.Close();

}

}

{

registration.Show();

Close();

}

}

}

"Sorry! Please enter existing emailid/password.";private void buttonRegister_Click(object sender, RoutedEventArgs e)