Why are bookmarks generated intermittently when PDF created using EXCEL VBA?

Question

I have Windows 7 installed and Acrobat Pro 9 installed. There is an EXCEL application that creates PDFs successfully. Howver, bookmarks are generated sometimes and sometimes they are not generated. This happens without changing any code. I am at my wits end and would appreciate any assistance. Here is the code:
Function PDF_PRINTING_2007()
Dim V_NBR_OF_RPTS As Integer
Dim stdPrinter As String
Dim Prints, z, n As Integer
Dim pdfile, pdtitle As Boolean
Dim V_RPT_ARRAY(800) As String
Dim V_RPT_PAGES_ARRAY(800) As Long
    Application.ScreenUpdating = False
    V_NBR_OF_RPTS = 0
    Erase V_RPT_ARRAY
    Erase V_RPT_PAGES_ARRAY
    V_PLANT_SUMMARY = ""
    Sheets("TABLE OF CONTENTS").Activate
    V_TOC_LAST_ROW = Cells(65536, 7).End(xlUp).Row
    V_TOC_ROW = 5
    Do Until V_TOC_ROW > V_TOC_LAST_ROW
        If Cells(V_TOC_ROW, 7) = "Y" Then
            V_RPT = Cells(V_TOC_ROW, 2).Value
            If V_RPT = "PLANT SUMMARY" Then
                V_PLANT_SUMMARY = "Y"
            End If
            If V_RPT = UCase("SUMMARY CAGE & HOIST") Or V_RPT = UCase("PLANT SUMMARY") Then
            Else
                V_NBR_OF_RPTS = V_NBR_OF_RPTS + 1
                V_RPT_ARRAY(V_NBR_OF_RPTS) = V_RPT
                V_RPT_PAGES_ARRAY(V_NBR_OF_RPTS) = Cells(V_TOC_ROW, 6)
            End If
        End If
        V_TOC_ROW = V_TOC_ROW + 1
    Loop
    Sheets("SYS - USER INTERFACE").Activate
    V_RPT_PERIOD = Cells(1, 1)
    V_PLANT_NBR = Cells(1, 2)
    V_PLANT_NAME = Cells(1, 3)
    Set AcroApp = CreateObject("AcroExch.App")
    Set PDBookmark = CreateObject("AcroExch.PDBookmark")
    Set avDoc = CreateObject("AcroExch.AVDoc")
    Set pdDoc1 = CreateObject("AcroExch.PDDoc")
    Set pdDoc2 = CreateObject("AcroExch.PDDoc")
    'Print Worksheets to PDF Files
    stdPrinter = Application.ActivePrinter
    'Commented out next line for Acrobat 8.x - 1/29/2008 - CR24709 and WP25089
    ' Application.ActivePrinter = "Acrobat PDFWriter on LPT1:"
    AppendIni ("C:\temp\Sheet1.pdf")
    'Commented out next line for Acrobat 8.x - 1/29/2008 - CR24709 and WP25089
    'Sheets("COVER SHEET").PrintOut
    'Added the next 3 lines for Acrobat 8.x - 1/29/2008 - CR24709 and WP25089
    Sheets("COVER SHEET").Activate
    PageSetupFitToPage
    SaveToPDF ("C:\temp\Sheet1.pdf")
    pdDoc1.Open ("C:\temp\Sheet1.pdf")
    pdDoc1.SetInfo "Title", "Cover Sheet"
    pdDoc1.Save 1, "C:\temp\Sheet1.pdf"
    pdDoc1.Close
' The "TABLE OF CONTENTS" worksheet contains color.  Reset it to black and white.
    Application.DisplayAlerts = False
    On Error Resume Next
    Worksheets("SYS - PDF WS").Delete
'EOB change for Priority #12--Arial named range dialog box error
'  Comment out alert below
'    Application.DisplayAlerts = True
'EOB change for Priority #12 end
    Sheets("TABLE OF CONTENTS").Copy Before:=Sheets("SYS - USER INTERFACE")
    ActiveSheet.Name = "SYS - PDF WS"
'EOB change for Priority #12--Arial named range dialog box error
'  insert alert below
    Application.DisplayAlerts = True
'EOB change for Priority #12 end
    Sheets("TABLE OF CONTENTS").Activate
    V_TOC_ROW = 5
    Do Until V_TOC_ROW > V_TOC_LAST_ROW
        If Cells(V_TOC_ROW, 7) = "Y" Then
            V_RPT_NAME = Cells(V_TOC_ROW, 2)
            Cells(V_TOC_ROW, 2).Clear
            Cells(V_TOC_ROW, 2) = V_RPT_NAME
        End If
        V_TOC_ROW = V_TOC_ROW + 1
    Loop
    Cells.Select
    Selection.Font.Color = vbBlack
    Selection.Interior.Color = vbWhite
     AppendIni ("C:\temp\Sheet2.pdf")
     'Commented out next line for Acrobat 8.x - 1/29/2008 - CR24709 and WP25089
     'Sheets("TABLE OF CONTENTS").PrintOut
     'Added the next 3 lines for Acrobat 8.x - 1/29/2008 - CR24709 and WP25089
     Sheets("TABLE OF CONTENTS").Activate
     PageSetupFitToPageWidth
     SaveToPDF ("C:\temp\Sheet2.pdf")
     pdDoc2.Open ("C:\temp\Sheet2.pdf")
     pdDoc2.SetInfo "Title", "Table of Contents"
     pdDoc2.Save 1, "C:\temp\Sheet2.pdf"
     pdDoc2.Close
    Application.DisplayAlerts = False
    Worksheets("TABLE OF CONTENTS").Delete
    Sheets("SYS - PDF WS").Copy Before:=Sheets("TEMPLATE TBL OF CONTENTS")
    ActiveSheet.Name = "TABLE OF CONTENTS"
    Worksheets("SYS - PDF WS").Delete
    Application.DisplayAlerts = True
    Prints = 3
    If V_PLANT_SUMMARY = "Y" Then
        Sheets("PLANT SUMMARY").Activate
        Sheets("PLANT SUMMARY").PageSetup.LeftFooter = Now()
        Sheets("PLANT SUMMARY").PageSetup.CenterFooter = "#" & V_PLANT_NBR & " " & V_PLANT_NAME & Chr(13) & V_RPT_PERIOD
        'Sheets("PLANT SUMMARY").PageSetup.RightFooter = "Page 1"
        'eob change start here--Change #9 comment out page numbers
        'Sheets("PLANT SUMMARY").PageSetup.RightFooter = "Page " & Prints
        'eob change end
        AppendIni ("C:\temp\Sheet" & Prints & ".pdf")
        'Commented out next line for Acrobat 8.x - 1/29/2008 - CR24709 and WP25089
        'Sheets("PLANT SUMMARY").PrintOut
        'Added the next 2 lines for Acrobat 8.x - 1/29/2008 - CR24709 and WP25089
         Sheets("PLANT SUMMARY").Activate
         SaveToPDF ("C:\temp\Sheet" & Prints & ".pdf")
         pdDoc2.Open ("C:\temp\Sheet" & Prints & ".pdf")
         pdDoc2.SetInfo "Title", "PLANT SUMMARY"
         pdDoc2.Save 1, "C:\temp\Sheet" & Prints & ".pdf"
         pdDoc2.Close
        Prints = Prints + 1
    End If
    V_RPT = 1
    On Error Resume Next   'DO NOT REMOVE THIS LINE
    Do Until V_RPT > V_NBR_OF_RPTS
    v_sheet_name = V_RPT_ARRAY(V_RPT)
        Sheets(v_sheet_name).Activate
        Sheets(v_sheet_name).PageSetup.LeftFooter = Now()
        Sheets(v_sheet_name).PageSetup.CenterFooter = "#" & V_PLANT_NBR & " " & V_PLANT_NAME & Chr(13) & V_RPT_PERIOD
        'eob change start here--Change #9 comment out page numbers
        'Sheets(v_sheet_name).PageSetup.RightFooter = "Page " & Prints
        'eob change end
        AppendIni ("C:\temp\Sheet" & Prints & ".pdf")
        'Commented out next line for Acrobat 8.x - 1/29/2008 - CR24709 and WP25089
        'Sheets(V_SHEET_NAME).PrintOut
        'Added the next 2 lines for Acrobat 8.x - 1/29/2008 - CR24709 and WP25089
         If v_sheet_name = "EXPLANATION OF PLANT VARS" Then
           PageSetupFitToPageWidth
         End If
         SaveToPDF ("C:\temp\Sheet" & Prints & ".pdf")
         pdDoc2.Open ("C:\temp\Sheet" & Prints & ".pdf")
         pdDoc2.SetInfo "Title", v_sheet_name
         pdDoc2.Save 1, "C:\temp\Sheet" & Prints & ".pdf"
        Sheets(v_sheet_name).DisplayPageBreaks = False
        Prints = Prints + 1
        pdDoc2.Close
        V_RPT = V_RPT + 1
    Loop
    Kill ActiveWorkbook.Path & "\New Costbook.pdf"
    'Consolidate PDF Files
    On Error GoTo Err1
    pdfile = avDoc.Open("C:\temp\Sheet1.pdf", "Window Title")
    Set pdDoc1 = avDoc.GetPDDoc
    AcroApp.MenuItemExecute ("NewBookmark")
    pdtitle = PDBookmark.GetByTitle(pdDoc1, "Untitled")
    pdtitle = PDBookmark.SetTitle("Cover Sheet")
    pdDoc1.Save 1, ActiveWorkbook.Path & "\New Costbook.pdf"
    For z = 2 To Prints
        n = pdDoc1.GetNumPages()
        pdDoc2.Open ("C:\temp\Sheet" & z & ".pdf")
        If pdDoc2.GetNumPages() <> 0 Then
            pdDoc1.InsertPages n - 1, pdDoc2, 0, pdDoc2.GetNumPages(), False
            Set avPageView = avDoc.GetAVPageView()
            avPageView.GoTo (n)
            AcroApp.MenuItemExecute ("NewBookmark")
            pdtitle = PDBookmark.GetByTitle(pdDoc1, "Untitled")
            pdtitle = PDBookmark.SetTitle(pdDoc2.GetInfo("Title"))
            pdDoc2.Close
            pdDoc1.Save 1, "C:\temp\Sheet1.pdf"
        Else
            pdDoc2.Close
        End If
    Next z
    avPageView.GoTo (0)
    pdDoc1.SetPageMode (3)
    pdDoc1.Save 1, ActiveWorkbook.Path & "\New Costbook.pdf"
    pdDoc1.Close
    Set AcroApp = Nothing
    Set PDBookmark = Nothing
    Set avDoc = Nothing
    Set pdDoc1 = Nothing
    Set pdDoc2 = Nothing
    Application.ScreenUpdating = True
    Sheets("SYS - USER INTERFACE").Activate
    AppActivate "Microsoft Excel"
    MsgBox "File Saved As: " & ActiveWorkbook.Path & "\New Costbook.pdf", vbInformation
    Application.ActivePrinter = stdPrinter
    Kill "C:\temp\Sheet*.pdf"
    Exit Function
Err1:
    AppActivate "Microsoft Excel"
    MsgBox Err.Description
    Application.ActivePrinter = stdPrinter
End Function

Answer 1

Acrobat Scripting Forum http://forums.adobe.com/community/acrobat/acrobat_scripting
or more likely
Acrobat SDK Developer Forum http://forums.adobe.com/community/acrobat/acrobat_sdk