help me with an error please

SqlConnection con = new SqlConnection("Data Source=GITTWO-PC\\sql2008R2;Initial Catalog=Application;Integrated Security=SSPI");
           con.Open();
           SqlCommand cmd = new SqlCommand("validateuser", con);
           cmd.CommandType = CommandType.StoredProcedure;
           cmd.Parameters.AddWithValue("@username", textBox1.Text);
           cmd.Parameters.AddWithValue("@password", textBox2.Text);
           cmd.Parameters.Add("@result", SqlDbType.Int).Direction = ParameterDirection.Output;
           cmd.ExecuteNonQuery();
           int result = int.Parse(cmd.Parameters["@result"].Value.ToString());
           if (result == 1)
           {
               Form2 frm = new Form2();
               frm.Show();
           }
           else if (result == 2)
           {
               //MessageBox.Show("Invalid Password", "Invalid Password");
               label3.Visible = true;
               label3.Text = "Invalid Password.......!!!";
           }
           else if (result == 3)
           {
               //MessageBox.Show("Invalid User Name", "Invalid User Name");
               label3.Text = "Invalid UserName.......!!!";
           }
           else if (result == 4)
           {
               //MessageBox.Show("Invalid User Name & Password", "Invalid User Name & Password");
               label3.Text = "Invalid UserName and Password.......!!!";

           }
           con.Close();