Specifying a sheet & range in ThisWorkbook module

Hi All,

I'm sure this is really simple but I just can't figure out what's wrong
I have a small piece of code in the 'ThisWorkbook' module that changes a specific cell from FALSE/TRUE whenever the workbook is saved

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
    Range("N149").Select
    ActiveCell.FormulaR1C1 = "FALSE"
End Sub
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Private Sub Workbook_AfterSave(ByVal Success As Boolean)
    Range("N149").Select
    ActiveCell.FormulaR1C1 = "TRUE"
End Sub

Unfortunately this code executes on whichever sheet I am on at the time
How can I specify which sheet this should run on?

I've tried the following

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
    Sheets("INV & CRN").Range("N149").Select
    ActiveCell.FormulaR1C1 = "FALSE"
End Sub

But this gives "Runtime error 1004 - select method of range class failed"

And also

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
    With ThisWorkbook.Sheets("INV & CRN")
    Range("N149").Select
    ActiveCell.FormulaR1C1 = "FALSE"
    End With
End Sub

But this still executes on the active sheet rather than sheet4 ("INV & CRN")

Any help would be appreciated
Kind regards
V