Generating PDf from Multiple Excel sheet using VB.net

   Dim fileName As String = AppDomain.CurrentDomain.BaseDirectory & "WeeklyReport"
   Dim xlsApp = New Microsoft.Office.Interop.Excel.Application
  xlsApp.ScreenUpdating = False
   Dim xlsBook As Microsoft.Office.Interop.Excel.Workbook
    Dim paramOpenAfterPublish As Boolean = False
    Dim paramIncludeDocProps As Boolean = True
    Dim paramIgnorePrintAreas As Boolean = True
   Dim paramFromPage As Object = Type.Missing
     Dim paramToPage As Object = Type.Missing
    xlsBook = xlsApp.Workbooks.Open(fileName & ".xls", UpdateLinks:=False, ReadOnly:=False)

xlsBook.ExportAsFixedFormat(Microsoft.Office.Interop.Excel.XlFixedFormatType.xlTypePDF, fileName & ".pdf", Microsoft.Office.Interop.Excel.XlFixedFormatQuality.xlQualityStandard, paramIncludeDocProps, paramIgnorePrintAreas, paramFromPage, paramToPage, paramOpenAfterPublish)
 '    xlsBook.ExportAsFixedFormat(Microsoft.Office.Interop.Excel.XlFixedFormatType.xlTypePDF, fileName & ".pdf", Microsoft.Office.Interop.Excel.XlFixedFormatQuality.xlQualityStandard, Type.Missing, False, Type.Missing, Type.Missing, False, Type.Missing)
  xlsBook.Close(SaveChanges:=False)
    xlsApp.Quit()