Concaténer 2 colonnes suivant leurs noms définis

col1 = 5 'Premiere colonne
col2 = 7 'Seconde colonne

r1 = Cells(2, col1).Address(ColumnAbsolute:=False, rowAbsolute:=False)
r2 = Cells(2, col2).Address(ColumnAbsolute:=False, rowAbsolute:=False)
'....
.Cells(2, "AT").FormulaLocal = "=" & r1 & "&" & r2

lettre1 = Split(Cells(2, col1).Address(columnAbsolute:=False), "$")(0)

Sub test()
Dim dl&, colA$, colB$
Sheets("DT").Activate
With Sheets("DT")
    dl = .Cells(Rows.Count, "A").End(xlUp).Row
    colA = "F": colB = "O"
    .Range("AT1") = "ConcatenerDT"
    .Cells(2, "AT").Resize(dl).FormulaLocal = "=" & colA & "2&" & colB & "2"
    With .Range("AT:AT")
        .NumberFormat = "General"
        .HorizontalAlignment = xlCenter
    End With
End With
End Sub