Private Sub Worksheet_Change(ByVal Target As Range)
Dim xcell
Application.EnableEvents = False
On Error GoTo FIN
For Each xcell In Intersect(Target, Range("a3:a" & Rows.Count))
If xcell = "" Then
xcell.Offset(, 1) = Empty
Else
xcell.Offset(, 1).FormulaR1C1 = _
"=IFERROR(VLOOKUP(RC[-1],'Affectation Tram'!R1C25:R99999C26,2,FALSE),"""")"
xcell.Offset(, 1).Value = xcell.Offset(, 1)
End If
Next xcell
FIN:
Application.EnableEvents = True
End Sub