void BillingEngine_EinvNodeAdding(object sender, MercatorUi.Engine.Gescom.BillingEngine.EinvNodeAddingEventArgs e)
{
    MercatorUi.Engine.Gescom.BillingEngine billingEngine = (MercatorUi.Engine.Gescom.BillingEngine)sender;
    if ((e.Node.Name == "cbc:Note") && e.ParentNode.LocalName.EqualsOr("Invoice", "CreditNote"))
    {
        if (billingEngine.PIEDS["note2"].ToString().Trim() == string.Empty)
            e.Cancel = true;
        else
            e.Node.InnerText = billingEngine.PIEDS["note2"].ToString().Trim();
    }
}