Creating Excel Toolbar in VBA - getting compile error

I'm trying to create a toolbar that will allow the user to toggle hiding or unhiding certain columns in the opened file.
I combined 2 EE solutions to come up with the code, but when I open or close Excel, the following error appears
with Sub Workbook_BeforeClose() highlighted.

Compile error: Procedure declaration does not match description of event or procedure having the same name.

Can you tell me how to correct the following code? It has been saved as MyToolBar.xla in XLStart with IsAddin = True.
Could be as simple as the fact that I capitalized the "B" in the name of the .xla file?  

Option Explicit
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Sub Workbook_Open()

'When any workbook is opened in Excel, a custom toolbar is created
    Call CreateToolBar
End Sub
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Sub Workbook_BeforeClose()

'Just before the workbook is closed, the custom toolbar is deleted
    Call RemoveToolBar
End Sub
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Sub CreateToolBar()

' Create and display a toolbar with one button that when clicked
' calls the ToggleView procedure.

    With Application.CommandBars.Add("MyToolbar")
        .Visible
        .Position = msoBarTop
        .Protection = msoBarNoMove + msoBarNoChangeVisible
        With .Controls
            With .Add(msoControlButton)
                .Style = msoButtonIconAndCaption
                .FaceId = 19
                .Caption = "Hide Known Columns"
                .OnAction = ThisWorkbook.Name & "!ToggleView"
                .BeginGroup = True
            End With
        End With
    End With
End Sub
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Sub RemoveToolBar()
    Toolbars("MyToolbar").Delete
End Sub
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Sub ToggleView()

'This macro hides/unhides columns A, C through H and AA through AZ.

'Declare a variable
    Dim IsHidden As Boolean
   
'Make sure a cell is active
    ActiveCell.Activate

'Check hidden state of one of the columns
    IsHidden = ActiveSheet.Range("C:C").EntireColumn.Hidden

'Change hidden state of some columns
    ActiveSheet.Range("A:A,C:H,AA:AZ").EntireColumn.Hidden = Not IsHidden

End Sub
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Thank you for any help you can give!