ASP.net VB2010 ออกรายงาน excel error แบบนี้คับ แก้อย่างไรคับ

  Private Sub report()
        Dim i As Integer = 0
        Dim j As Integer = 7
        Dim ExcelApp As Excel.Application
        Dim ExcelBooks As Excel.Workbook
        Dim ExcelSheets As Excel.Worksheet
        ExcelApp = New Excel.Application
        Dim chartRange As Excel.Range

        ExcelApp.Visible = True
        ExcelBooks = ExcelApp.Workbooks.Add()
        ExcelSheets = DirectCast(ExcelBooks.Worksheets(1), Excel.Worksheet)

        Dim dsChk As New DataSet
        Dim sqlselect As String = ""
        Dim title As String = ""
        Dim addmem As String = ""
        Dim telmem As String = ""

        chartRange = ExcelSheets.Range("A3", "H3")
        chartRange.Merge()
        chartRange.FormulaR1C1 = "รายงานผลประจำวัน"
        chartRange.Font.Size = 28
        chartRange.HorizontalAlignment = Excel.XlHAlign.xlHAlignCenter

        chartRange = CType(ExcelSheets.Range("A4", "H4"), Excel.Range)
        chartRange.Merge()
        chartRange.FormulaR1C1 = "รายงานสรุปการสั่งซื้อวัสดุสำหรับการฝึกซ้อมประจำ"
        chartRange.Font.Size = 28
        chartRange.HorizontalAlignment = Excel.XlHAlign.xlHAlignCenter
        With ExcelSheets.PageSetup     ''ออกรายงานแนวนอน
            '.PrintArea = Range("landscape").Address
            .Orientation = Excel.XlPageOrientation.xlLandscape
        End With

        With ExcelSheets
            .Columns.Font.Name = "Angsana New"
            .Columns.Font.Size = 16
            .Columns().ColumnWidth = 12

            .Range("F1").Value = "วันที่ออกรายงาน"

        End With

        ExcelSheets = Nothing
        ExcelBooks = Nothing
        ExcelApp = Nothing
    End Sub