Vérification de nom d'onglet

Function FExist(NomF As String) As Boolean ' test si la feuille existe
   Application.ScreenUpdating = False
   On Error Resume Next
   FExist = Not Sheets(NomF) Is Nothing
   Application.ScreenUpdating = True
End Function 

Sub ajoutProduction()
'
' ajoutProduction Macro
'
   Dim nomF as String
    nomF = Format(Date, "dd-mm-yy")
    if FExist(nomF) Then 
      exit sub
    End If

    ActiveWorkbook.Unprotect
    Sheets("Suivi Production").Select
    Sheets("Suivi Production").Copy After:=Sheets(1)

    ActiveSheet.Name = nomF
    ActiveWorkbook.protect Structure:=True, Windows:=False

    
End Sub

Option Explicit

Sub ajoutProduction()
'
' ajoutProduction Macro
'
Dim nom As String
nom = Format(Date, "dd-mm-yy")
If Not existedeja(nom) Then
    ActiveWorkbook.Unprotect
    Sheets("Suivi Production").Select
    Sheets("Suivi Production").Copy After:=Sheets(1)
    ActiveSheet.Name = Format(Date, "dd-mm-yy")
    ActiveWorkbook.Protect Structure:=True, Windows:=False
End If
    
End Sub
Private Function existedeja(quoi As String) As Boolean
Dim ong As Worksheet
For Each ong In ThisWorkbook.Worksheets
    If ong.Name = quoi Then
        existedeja = True
        Exit Function
    End If
Next ong
existedeja = False
End Function

Function FeuilleExiste(ByVal strNomFeuille As String) As Boolean
  FeuilleExiste = Not IsError(Evaluate("='" & strNomFeuille & "'!A1"))
End Function