vb.net ผมไม่สามารถปิด excel ที่อ่านได้ครับ มันเลยไม่สามารถลบไฟร์ที่ใช้งานได้ รบกวนหน่อยนะคับ

         Dim fn As String = System.IO.Path.GetFileName(FileUpload1.PostedFile.FileName)
            Dim parth As String = Server.MapPath("~/Upload/" + fn)
            Dim xlApp As New excel.Application
            Dim xlBook As excel.Workbook
            Dim xlSheet1 As excel.Worksheet
            FileUpload1.PostedFile.SaveAs(parth)
            Dim i As Integer = 1
            xlBook = xlApp.Workbooks.Open(parth)
            'xlBook.Application.Visible = False
            xlSheet1 = xlBook.Worksheets("LoadData")
            Dim dt As New System.Data.DataTable
            Dim dr As System.Data.DataRow
            dt.Columns.Add("locid")
            dt.Columns.Add("GroupWork")
            Do While Not Trim(xlSheet1.Cells.Item(i, 1).Value) = ""
                dr = dt.NewRow
                dr("locid") = xlSheet1.Cells.Item(i, 1).Value
                dr("GroupWork") = xlSheet1.Cells.Item(i, 2).Value
                dt.Rows.Add(dr)
                i = i + 1
            Loop
            Dim buss As New CommonBusinessProcess.CommonBusinessProcess
            Dim sql As String = String.Empty
            For j As Integer = 0 To dt.Rows.Count - 1
                sql = sql + "  INSERT INTO [dbo].[tb_mapLocationWork]([locid],[Group_work_id])VALUES('" + dt.Rows(j)    ("locid").ToString().Trim() + "','" + dt.Rows(j)("GroupWork").ToString().Trim() + "')"
            Next
            buss.ManageSQLString(sql)
            dt = Nothing

          
            xlBook.Close()
            xlApp.Quit()
            System.Runtime.InteropServices.Marshal.ReleaseComObject(xlSheet1)
            System.Runtime.InteropServices.Marshal.ReleaseComObject(xlBook)
            System.Runtime.InteropServices.Marshal.ReleaseComObject(xlApp)
            Dim MyFile As New FileInfo(parth)
            If MyFile.Exists Then
                MyFile.Delete()
            End If