How to select weekend dates in calender control on button click

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

        'To select SaturDay in the selected week

        Calendar1.SelectedDates.Add(Calendar1.SelectedDate.AddDays(6 - CInt((Calendar1.SelectedDate).DayOfWeek)))

        'To select Sunday in the selected week

        Calendar1.SelectedDates.Add(Calendar1.SelectedDate.AddDays(7 - CInt((Calendar1.SelectedDate).DayOfWeek)))

    End Sub

Partial Class SelectWeekEnds

    Inherits System.Web.UI.Page

    Dim btnclick As Boolean = False

    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)

        If btnclick = True Then

            If CInt(e.Day.Date.DayOfWeek) = 0 Or CInt(e.Day.Date.DayOfWeek) = 6 Then

                ctl.Checked = True

            End If

        End If

        e.Cell.Controls.Add(ctl)

    End Sub

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

        btnclick = True

    End Sub

End Class