calender events in .net with c#

i am making a dynamic website in which i have made a registration page.
in registration, i have to display dates chosen by user. so i have used calender.
but problem is that if one user has selected any date then if second user again selects same date then the nothing is printed in textbox. i think i am using wrong event handler for calender.

PLZ HELP

here is my code -->

1.  protected void Calendar1_SelectionChanged(object sender, EventArgs e)
2.     {
3.         System.DateTime myDate = new System.DateTime();
4.         myDate = Calendar1.SelectedDate;
5.         TextBox3.Text = myDate.ToString("dd/MM/yyyy");
6.     }