Liste de validation suivant conditions (VBA)

Dim Ws As Worksheet, Liste As String
    Liste = ""
    For Each Ws In ThisWorkbook.Worksheets
        If UCase(Ws.Range("A1").Value) = "OUI" And Ws.Range("A2").Value = 1 Then
            Liste = Liste & "," & Ws.Name
        End If
    Next Ws
    If Len(Liste) > 0 Then Liste = Right(Liste, Len(Liste) - 1)
    With Sheets("Feuil1").Range("C2").Validation
        .Delete
        .Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, Operator:= _
        xlBetween, Formula1:=Liste
        .IgnoreBlank = True
        .InCellDropdown = True
        .InputTitle = ""
        .ErrorTitle = ""
        .InputMessage = ""
        .ErrorMessage = ""
        .ShowInput = True
        .ShowError = True
    End With
End Sub

Sub tri(a, gauc, droi) ' Quick sort
'http://boisgontierjacques.free.fr/pages_site/formulairelistetriee.htm
   ref = a((gauc + droi) \ 2)
   g = gauc: d = droi
   Do
     Do While a(g) < ref: g = g + 1: Loop
     Do While ref < a(d): d = d - 1: Loop
     If g <= d Then
       temp = a(g): a(g) = a(d): a(d) = temp
       g = g + 1: d = d - 1
     End If
   Loop While g <= d
   If g < droi Then Call tri(a, g, droi)
   If gauc < d Then Call tri(a, gauc, d)
End Sub


Sub ListValid()
Dim Ws As Worksheet, Liste() As String
    ReDim Liste(0)
    For Each Ws In ThisWorkbook.Worksheets
        If UCase(Ws.Range("A1").Value) = "OUI" And Ws.Range("A2").Value = 1 Then
            Liste(UBound(Liste)) = Ws.Name
            ReDim Preserve Liste(UBound(Liste) + 1)
        End If
    Next Ws
    If UBound(Liste) > 0 Then ReDim Preserve Liste(UBound(Liste) - 1)
    Call tri(Liste, LBound(Liste), UBound(Liste))
    With Sheets("Feuil1").Range("C2").Validation
        .Delete
        .Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, Operator:= _
        xlBetween, Formula1:=Join(Liste, ",")
        .IgnoreBlank = True
        .InCellDropdown = True
        .InputTitle = ""
        .ErrorTitle = ""
        .InputMessage = ""
        .ErrorMessage = ""
        .ShowInput = True
        .ShowError = True
    End With
End Sub

Sub Macro1()
' Macro1 Macro
    With Selection.Validation
        .Delete
        .Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, Operator:= _
        xlBetween, Formula1:="=$A$1"
        .IgnoreBlank = True
        .InCellDropdown = True
        .InputTitle = ""
        .ErrorTitle = ""
        .InputMessage = ""
        .ErrorMessage = ""
        .ShowInput = True
        .ShowError = True
    End With
End Sub