private void Text20_BeforePrint(object sender, EventArgs e)
{
    List<MercatorUi.Engine.Gescom.Tools.PaymentTracingDescriptor> l = MercatorUi.Engine.Gescom.Tools.PaymentTracingDescriptor.ListFromJsonString((String)Report.GetColumnValue("PIEDS_V.PAYMENTS_TRACING"));
    double v = 0;
    foreach (MercatorUi.Engine.Gescom.Tools.PaymentTracingDescriptor d in l)
        v += d.TotDv;
    Text20.Text = FormatNumber(v,(Int16)Report.GetColumnValue("PIEDS_V.N_DEC"));
}