How to add appointments using a custom appointment form in WinForms ScheduleControl?

AppointmentForm form;
//Hook the event for showing the appointment form.
this.scheduleControl1.ShowingAppointmentForm += scheduleControl1_ShowingAppointmentForm;

/// <summary>
/// Raise the event when showing the appointment form
/// </summary>

void scheduleControl1_ShowingAppointmentForm(object sender, ShowingAppointFormEventArgs e)
{
   //Cancel the default appointment form for schedule control.
    e.Cancel = true;

    //Shows the Custom appointment form.
    form.ShowDialog();
}

Private form As AppointmentForm
'Hook the event for showing the appointment.
Private Me.scheduleControl1.ShowingAppointmentForm += AddressOf scheduleControl1_ShowingAppointmentForm

''' <summary>
''' Raise the event when showing the appointment form
''' </summary>

Private Sub scheduleControl1_ShowingAppointmentForm(ByVal sender As Object, ByVal e As ShowingAppointFormEventArgs)
    'Cancel the default appointment form for schedule control.
    e.Cancel = True

    ' Shows the Custom appointment form.
    form.ShowDialog()
End Sub

void ok_Click(object sender, System.EventArgs e)
{
    //Create a new schedule appointment
    IScheduleAppointment item = provider.NewScheduleAppointment();
    if (item != null)
    {
        item.AllDay = true;
        item.StartTime = this.StartDateDateTimePickerAdv.Value;
        item.EndTime = this.EndDateDateTimePickerAdv.Value;
        item.Subject = this.SubjectTextBoxExt.Text;
        item.LabelValue = this.comboBox1.SelectedIndex;
        //Appointment can be added in ScheduleDataProvider
        provider.AddItem(item);
    }
    this.schedulegrid.DataSource = provider;
    this.schedulegrid.GetScheduleHost().SetDataToDayPanels();
    this.Close();
}

Private Sub ok_Click(ByVal sender As Object, ByVal e As System.EventArgs)
      'Create a new schedule appointment
      Dim item As IScheduleAppointment = provider.NewScheduleAppointment()
      If item IsNot Nothing Then
            item.AllDay = True
            item.StartTime = Me.StartDateDateTimePickerAdv.Value
            item.EndTime = Me.EndDateDateTimePickerAdv.Value
            item.Subject = Me.SubjectTextBoxExt.Text
            item.LabelValue = Me.comboBox1.SelectedIndex
            'Appointment can be added in ScheduleDataProvider
            provider.AddItem(item)
      End If
      Me.schedulegrid.DataSource = provider
      Me.schedulegrid.GetScheduleHost().SetDataToDayPanels()
      Me.Close()
End Sub