Listbox in asp.net is not displaying the added items .

Question

public partial class Default : System.Web.UI.Page

{

private List<ClientReservationRoom> lista = new List<ClientReservationRoom>();

private List<RoomCheckout> room_checkout = new List<RoomCheckout>();

protected void Page_Load(object sender, EventArgs e)

{

}

protected void lnkpickdate_Click(object sender, EventArgs e)

{

datepicker.Visible = true;

txtdtp.Text = datepicker.SelectedDate.ToShortDateString();

}

protected void datepicker_SelectionChanged(object sender, EventArgs e)

{

txtdtp.Text = datepicker.SelectedDate.ToShortDateString();

datepicker.Visible = true;

}

protected void btnAddCustomer_Click(object sender, EventArgs e)

{

string name;

decimal number;

string type;

name = txtName.Text;

number = Convert.ToDecimal(txtPhone.Text);

type = cmbType.Text;

ClientReservationRoom clientreservation = new ClientReservationRoom(name, number, type);

lista.Add(clientreservation);

}

protected void btnListCustomers_Click(object sender, EventArgs e)

{

lbReservations.Items.Clear();

foreach (ClientReservationRoom reservationroom in lista)

lbReservations.Items.Add(reservationroom.DisplayName());

}

}