Add Check Box in Calender Control

Add Checkbox in Calender Control manually.

Code :

Partial Class SelectWeekEnds
  Inherits System.Web.UI.Page

  Protected Sub Calendar1_DayRender(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DayRenderEventArgs) Handles Calendar1.DayRender
      Dim ctl As New CheckBox
      ctl.ID = "chk" & e.Day.Date.ToString.Substring(0, 10)
      e.Cell.Controls.Add(ctl)
  End Sub  

End Class