Runtime error 1004 while loading Add-In

Hello:

I have a workopen event as follows:

Private Sub Workbook_Open()
	Application.MacroOptions Macro:="Fintest1", _
        Description:="Square", _
        Category:=14, _
        HelpContextID:=25, _
  HelpFile:=ThisWorkbook.Path & "\FinPak3test.chm"

End Sub

The workbook is saved as an xlam file.

If I open this file after Excel 2007 loads with file open menu
everything is fine. The code runs without error and
the helpcontext etc work just fine.

Now if I load the file as an add-in through the add-in
manger using the Excel Option menu it again works just fine.

But if I close Excel and then Open Excel (so that add-in
loads automatically) I get an error message that says:

Run-time error '1004'
Cannot edit a macro on a hidden workbook. Unhide
the working using the Unhide command.

Can someone help so that the code works when
add-in is loaded automatically?

Thanks.

How about placing the code in a routine within a standard code module and calling that using the OnTime method

Thisworkbook object

Private Sub Workbook_Open()
    
    Application.OnTime Now + TimeValue("00:00:00"), "AssignHelp"

End Sub

Standard code module

Public Sub AssignHelp()
    
    Application.MacroOptions Macro:="Fintest1", _
        Description:="Square", _
        Category:=14, _
        HelpContextID:=25, _
        HelpFile:=ThisWorkbook.Path & "\FinPak3test.chm"

    MsgBox "Assigned"  ' for testing only
    
End Sub

apparently the small delay in processing the command via the ONTIME rather than a direct Call allows excel to untwist it's knickers.