probleme setfocus

private Sub Tel_AfterUpdate()
Dim h As Double
Dim tablo
Dim strNum As String
Dim i As Byte
strNum = ""
If Not IsNumeric(Tel.Value) Then
        Cancel = True ' Annule la validation de contrôle
        MsgBox "Veuillez entrer un nombre !"
Else
With Tel
    If Len(Tel.Value) > 0 Then
        tablo = Split(Tel.Value, ".")
        For i = LBound(tablo) To UBound(tablo)
            If Len(tablo(i)) >= 10 Then
                strNum = strNum & ", " & Format(tablo(i), "00"" ""00"" ""00"" ""00"" ""00")
           Else:
                MsgBox "message"
               Tel.SetFocus
           End If
        Next i
    End If
    Tel.Value = Mid(strNum, 3)
End With
End If
End Sub