/// <summary>
        /// Load Document Details
        /// </summary>
        /// <returns>error message or null</returns>
        public override String LoadDocumentDetails()
        {
            SetC_Currency_ID(NO_CURRENCY);
            MRequisition req = (MRequisition)GetPO();

            SetDateDoc(req.GetDateDoc());
            SetDateAcct(req.GetDateDoc());
            // Amounts
            SetAmount(AMTTYPE_Gross, req.GetTotalLines());
            SetAmount(AMTTYPE_Net, req.GetTotalLines());
            // Contained Objects
            _lines = LoadLines(req);
            // log.fine( "Lines=" + _lines.length + ", Taxes=" + m_taxes.length);
            return(null);
        }