Private Sub SelectedIndexChanged(sender As Object, _
     e As System.EventArgs) Handles _
     cbo_Year.SelectedIndexChanged, cbo_Month.SelectedIndexChanged
 
     If cbo_Year.SelectedIndex = -1 Then
        bs.RemoveFilter()
     Else
        'Filter setzen: Datumswerte im Standardformat angeben
        Dim year As String = cbo_Year.SelectedItem.ToString
        Dim month As String = ""
        If cbo_Month.SelectedIndex > 0 Then
           month = cbo_Month.SelectedIndex.ToString()
        End If
 
        If String.IsNullOrEmpty(month) Then
           'ein ganzes Jahr filtern 
            bs.Filter = _
             "Date >= #1/1/" & year & "# AND Date <= #12/31/" & year & "#"
        Else
            'einen Monat im Jahr filtern
            Dim days As String = ""
            Select Case cbo_Month.SelectedIndex
               Case Is = 1, 3, 5, 7, 8, 10, 12
                  days = "31"
               Case Is = 4, 6, 9, 11
                  days = "30"
               Case Else
                  If Date.IsLeapYear(CInt(year)) Then
                     days = "29"
                  Else
                     days = "28"
                  End If                  
             End Select
 
             'alternativ:
             'days = Date.DaysInMonth(CInt(year), CInt(month)).ToString
 
             bs.Filter = "Date >= #" & month & "/1/" & year & _
             "# AND Date <= #" & month & "/" & days & "/" & year & "#"
        End If
     End If
  End Sub