if (MercatorUi.Globals.EngineBillingV.LastBilling != null)
    MercatorUi.Globals.Main.ShowBillingExisting(MercatorUi.Globals.EngineBillingV.LastBilling.TypeVA.ToString(), MercatorUi.Globals.EngineBillingV.LastBilling.Type, MercatorUi.Globals.EngineBillingV.LastBilling.Id, MercatorUi.Globals.EngineBillingV.LastBilling.Journal, MercatorUi.Globals.EngineBillingV.LastBilling.Piece);