Refresh data grafik di powerpoint 2010 tidak dilakukan melalui VBA

Saya mencoba memperbarui data grafik di Powerpoint menggunakan kode ini:

Sub test1()
    Dim chrt As Chart
    Dim wbChart As New Workbook
    Dim wsChart As New Worksheet

    Dim sh As Shape

    With ActivePresentation.Slides(2)
        For Each sh In .Shapes
            If sh.Name = "Dia2" Then Exit For
        Next
    End With

    Set chrt = sh.Chart
    chrt.ChartData.Activate
    Set wbChart = chrt.ChartData.Workbook
    Set wsChart = wbChart.Worksheets(1)
    wsChart.Range("A2").Value = "North"
    wsChart.Range("A3").Value = "South"
    wsChart.Range("A4").Value = "East"
    wsChart.Range("A5").Value = "West"
    wsChart.Range("B1").Value = "2009"
    wsChart.Range("C1").Value = "2010"
    wsChart.Range("D1").Value = "2011"
    wsChart.ListObjects("Tabelle1").Resize wsChart.Range("A1:e6")
    wsChart.Range("A6").Value = "Canada"
    wsChart.Range("B6").Value = "5"
    wsChart.Range("C6").Value = "4"
    wsChart.Range("D6").Value = "3"
    wsChart.Range("E1").Value = "2012"
    wsChart.Range("E2").Value = "4"
    wsChart.Range("E3").Value = "5"
    wsChart.Range("E4").Value = "2"
    wsChart.Range("E5").Value = "3"
    wsChart.Range("E6").Value = "6"
    wbChart.Close

    sh.Chart.SetSourceData ("='Tabelle11'!$A$1:$E$6")
    sh.Chart.Refresh

End Sub

Semuanya berfungsi kecuali baris terakhir: sh.Chart.SetSourceData ("='Tabelle11!$A$1:$E$6") dan sh.Chart.Refresh. Datanya sendiri diperbarui.

Ada ide?