Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.Value = "GO" Then
Dim NomFeuille As String, Test As Boolean, Ws As Worksheet
NomFeuille = "mafeuille"
For Each Ws In Worksheets
If Ws.Name = NomFeuille Then Test = True: Exit For
Next Ws
If Test Then
Sheets(NomFeuille).Select
Else
Sheets("modele_feuille").Copy After:=Sheets(Sheets.Count)
ActiveSheet.Name = NomFeuille
End If
End If
End Sub