VBA Stop Workbook From Closing Unless Data Is Filled Complete

[Excel Fox]

Try this

Private Sub Workbook_BeforeClose(Cancel As Boolean)  Dim FilledCellCount As Long
  Dim lngRows As Long
  Const SheetContainingtheCells As String = "Sheet2"
  Const CellsToCheck As String = "M|:O|"
  For lngRows = 5 To 150
    If Not IsEmpty(Worksheets(SheetContainingtheCells).Range("G" & lngRows)) Then
        FilledCellCount = WorksheetFunction.CountA(Worksheets(SheetContainingtheCells).Range(Replace(CellsToCheck, "|", lngRows)))
        If FilledCellCount < 3 Then
            Cancel = True
            MsgBox "Since you filled the Range 'G" & lngRows & _
                 "' then you must fill in the corresponding cells in the range - " & Replace(CellsToCheck, "|", lngRows), vbExclamation
            Exit Sub
        End If
    End If
  Next lngRows
End Sub