[VBA] mise à jour liste déroulante combobox

Dim i As Long

i = 2
While Worsheets("Feuil4").Range("A" & i).Value <> "" 
    UserForm1.ComboBox1.Additem Worsheets("Feuil4").Range("A" & i).Value 
    i = i + 1
Wend

Private Sub bouton_Ok_Click()
Dim i As Long

i = 2
   If doesExist(ComboBox1.Text) = False Then
      While Worsheets("Feuil4").Range("A" & i).Value <> "" 
          i = i + 1
      Wend
      Worsheets("Feuil4").Range("A" & i + 1).Value = ComboBox1.Text
  End If
  ComboBox1.Clear
  Call InitialiseComboBox
End Sub

Private Function doesExist(ByVal str As String) As Boolean
Dim i As Long

i = 2
   While Worsheets("Feuil4").Range("A" & i).Value <> "" 
      If  Worsheets("Feuil4").Range("A" & i).Value = str Then
          doesExist = True
          Exit Function
     End If
   i = i + 1
   Wend
doesExist = False
End Function

Private Sub InitialiseComboBx()
Dim i As Long

i = 2
ComboBox.Clear
While Worsheets("Feuil4").Range("A" & i).Value <> "" 
    ComboBox1.Additem Worsheets("Feuil4").Range("A" & i).Value 
    i = i + 1
Wend
End Sub