Count hidden cells withing range

Hello everybody
I have this function that counts the hidden cells in a range
I want to update results after hiding and unhiding

Function CountHiddenCells(Rng As Range)
    Dim Counter As Long, Cell As Range
        Application.Volatile
        For Each Cell In Rng
            If Cell.ColumnWidth = 0 Or Cell.RowHeight = 0 Then Counter = Counter + 1
        Next Cell
    CountHiddenCells = Counter
End Function

I tried Application.volatile but I had to double click in any cell to update results !!