Compter les numéros d'immatriculation ?

Option Explicit
Private Sub CommandButton1_Click()
Dim plus As String
Dim moins As String
plus = InputBox("Saisie plus grande immatriculation : ", "Immatriculation", "GH-321-VA")
plus = NLib(plus)
moins = InputBox("Saisie plus petite immatriculation : ", "Immatriculation", "AB-425-CC")
moins = NLib(moins)
MsgBox (plus - moins)
End Sub
'https://www.excel-downloads.com/threads/incrementation-da-lalphabet-pour-calcul-nb-nouvelle-plaque-immat.141512/
Function NLib(r$)
'Exemple : transforme BQ-020-YC en 20 000 000
Application.Volatile
Dim a$, ch$, sp
  ch = "ABCDEFGHJKLMNPQRSTVWXYZ"
  a = Replace(r, "-", Space(1))
  If a Like "[A-Z][A-Z] ### [A-Z][A-Z]" And Not (a Like "*000*" Or a Like "*[IOU]*" Or a Like "*SS*" Or a Like "WW*") Then
    sp = Split(a)
    NLib = 999 * (528 * (23 * (InStr(1, ch, Left$(sp(0), 1))) + (InStr(1, ch, Right$(sp(0), 1))) + _
      (sp(0) > "SR") + (sp(0) > "WV")) + 23 * InStr(1, ch, Left$(sp(2), 1)) + _
      (InStr(1, ch, Right$(sp(2), 1))) + (sp(2) > "SR") - 12696) + sp(1)
  Else
    NLib = ""
  End If
End Function