problem missed formulas in TOTAL row when add new columns

[abdo meghari]

Hi
I got help from Maras_mak in old thread . every thing is ok except one thing is not adding formulas for row TTL for columns Arrived & Sales . the code will insert three columns for next month with the same formatting and formules .
here is the code

Option Explicit

Sub InsertMonth()
    Dim rng As Range
    Dim oldmth As String, mystr As String
    Dim oldm As Integer, newm As Integer
    Dim am
    
    am = [{"JANUARY", "FEBRUARY", "MARCH", "APRIL", "MAY", "JUNE", "JULY", "AUGUST", "SEPTEMBER", "OCTOBER", "NOVEMBER", "DECEMBER"}]
    Application.ScreenUpdating = False
    Application.Calculation = xlManual
    With Sheets(1)
        oldmth = (.Cells(1, Columns.Count).End(xlToLeft)(1, 1))
        oldm = Application.Match(oldmth, am, 0)
        newm = Month(DateSerial(Year(Now), oldm + 1, 1))
        
        .Cells(2, Columns.Count).End(xlToLeft)(1, -1).Resize(.[a2].CurrentRegion.Rows.Count - 1, 3).Copy _
                Cells(2, Columns.Count).End(xlToLeft)(1, 2)
        .Cells(2, Columns.Count).End(xlToLeft)(1, -1).Offset(1).Resize(.[a2].CurrentRegion.Rows.Count, 1).Resize(, 3).ClearContents
        If .Cells(1, Columns.Count).End(xlToLeft)(1, 1).Value <> "JANUARY" Then
            .Cells(2, Columns.Count).End(xlToLeft)(1, -1).Offset(1, -1).Resize(.[a2].CurrentRegion.Rows.Count, 1).Copy
            .Cells(2, Columns.Count).End(xlToLeft)(1, 1).Offset(1).Resize(.[a2].CurrentRegion.Rows.Count, 1).PasteSpecial xlPasteFormulas
        Else
            Sheets("Helper").Cells(2, Columns.Count).End(xlToLeft)(1, 1).Resize(.[a2].CurrentRegion.Rows.Count - 3).Offset(1).Copy
            .Cells(2, Columns.Count).End(xlToLeft)(1, 1).Offset(1).PasteSpecial xlPasteFormulas
        End If
        .Cells(1, Columns.Count).End(xlToLeft)(1, 1).Offset(, 1).Value = _
                        Choose(newm, "JANUARY", "FEBRUARY", "MARCH", "APRIL", "MAY", "JUNE", "JULY", "AUGUST", "SEPTEMBER", "OCTOBER", "NOVEMBER", "DECEMBER")
        With .Cells(1, Columns.Count).End(xlToLeft)(1, 1).Resize(, 3)
            .Merge
            .HorizontalAlignment = xlCenter
            .Font.ColorIndex = 1
            .Interior.ColorIndex = 6
             .Font.Size = 12

        End With
        .Cells(2, Columns.Count).End(xlToLeft)(1, 1).Offset(1).Select
        Application.CutCopyMode = False
        Application.Calculation = xlCalculationAutomatic
    End With
End Sub

thanks