Message d'erreur avec VB

Private Sub CommandButton3_Click()
'Dim L As Integer
Dim L As Long
If MsgBox("Confirmez-vous l'insertion de ce nouveau contact ?", vbYesNo, "Demande de confirmation d'ajout") = vbYes Then
    With Sheets("Clients")
       ' L = .Range("A65536").End(xlUp).Row + 1
       L = .Range("A" & Rows.Count).End(xlUp).Row + 1
        .Range("A" & L).Value = ComboBox1.Value
        .Range("B" & L).Value = ComboBox2.Value
        .Range("C" & L).Value = TextBox1.Value
        .Range("D" & L).Value = TextBox2.Value
        .Range("E" & L).Value = TextBox3.Value
        .Range("F" & L).Value = TextBox4.Value
        .Range("G" & L).Value = TextBox5.Value
        .Range("H" & L).Value = TextBox6.Value
        .Range("I" & L).Value = TextBox7.Value
        .Range("J" & L).Value = TextBox8.Value
        .Range("K" & L).Value = TextBox9.Value
        .Range("L" & L).Value = TextBox10.Value
        .Range("M" & L).Value = TextBox11.Value
        .Range("N" & L).Value = TextBox12.Value
    End With
End If
End Sub