Null value set to Datetimepicker

public partial class mst_item : Form
    {
        SqlConnection cn = null;
        int originalExStyle = -1;
        bool enableFormLevelDoubleBuffering = true;
        void dtBirthdayNullable_Format(object sender, ConvertEventArgs e)
        {
            // e.Value is the object value, we format it to be what we want to show up in the control 
            Binding b = sender as Binding;
            if (b != null)
            {
                dtBirthdayNullable  = (b.Control as DateTimePicker);

                if (dtBirthdayNullable != null)
                {
                    if (e.Value == null)
                    {
                        dtBirthdayNullable.ShowCheckBox = true;
                        dtBirthdayNullable.Checked = false;
                        e.Value = dtBirthdayNullable.Value;
                    }

                    else
                    {
                        dtBirthdayNullable.ShowCheckBox = true;
                        dtBirthdayNullable.Checked = true;
                        // leave e.Value unchanged – it’s not null, so the DTP is fine with it. 
                    }
                }
            }
        }
        //Binding v    = new Binding("Value");
        //Binding b = new Binding( "Value", person, "BdayNullable", true ); 
        // dtBirthdayNullable.DataBindings.Add( b );  
        //  b.Format += new ConvertEventHandler( dtBirthdayNullable_Format ); 
    
        void dtBirthdayNullable_Parse(object sender, ConvertEventArgs e)
        {
            // e.value is the formatted value coming from the control.   
            // we change it to be the value we want to stuff in the object. 

            Binding b = sender as Binding;

            if (b != null)
            {
                dtBirthdayNullable = (b.Control as DateTimePicker);

                if (dtBirthdayNullable != null)
                {
                    if (dtBirthdayNullable.Checked == false)
                    {
                        dtBirthdayNullable.ShowCheckBox = true;
                        dtBirthdayNullable.Checked = false;
                        System.Nullable(e.Value);
                        e.Value = new Nullable() ;
                    }

                    else
                    {
                        DateTime val = Convert.ToDateTime(e.Value);
                        e.Value =  new Nullable();
                    }

                }

            }

        } 

               private void mst_item_Load(object sender, EventArgs e)
        {
            try
            {
                cn.Open();
                SqlCommand cmd = new SqlCommand("Select date1 from datetime", cn);
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                DataSet ds = new DataSet();
                da.Fill(ds, "datetime");
                Binding b = new Binding("Value", ds, "datetime.date1", true);
                dtBirthdayNullable.DataBindings.Add(b);
                b.Format += new ConvertEventHandler(dtBirthdayNullable_Format);
                b.Parse += new ConvertEventHandler(dtBirthdayNullable_Parse);
            }
            catch(Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }