Сохранение значения dateTimePicker - C#

            int s;
            SaveFileDialog saveFileDialog = new SaveFileDialog();
            if (saveFileDialog.ShowDialog() == DialogResult.OK)
            {
              
                s = Convert.ToDateTime(dateTimePicker1.Text);
                System.IO.StreamWriter fileWrite = new
                    System.IO.StreamWriter(saveFileDialog.FileName);               
                fileWrite.WriteLine(s);
                fileWrite.Close();
            }