Test existence de feuille

Option Explicit

Private Function FeuilleExiste(ByVal sNom As String) As Boolean
  On Error Resume Next
  FeuilleExiste = Sheets(sNom).Name <> ""
  Err.Clear
End Function

Sub Tst()
Dim NomFeuille As String

    NomFeuille = "Feuil1"
    If FeuilleExiste(NomFeuille) Then
        Debug.Print NomFeuille & " existe"
    Else
        Debug.Print NomFeuille & " n'existe pas"
    End If
End Sub

Option Explicit
 
 Sub NouvelleFeuille()
   Dim n As Byte
   Dim Nom As String
   Nom = ActiveSheet.Name
   For n = 1 To Sheets.Count
     If Sheets(n).Name = [A1] Then MsgBox "Existe !": Exit Sub
   Next
   Sheets.Add
   ActiveSheet.Name = Sheets(Nom).[A1]
 End Sub