public virtual List <tbt_MonthlyBillingHistory> GetBillingHistoryPeriodList(string contractCode, string billingOCC, Nullable <System.DateTime> fromDate, Nullable <System.DateTime> toDate) { BLDataEntities context = new BLDataEntities(); return(context.GetBillingHistoryPeriodList(contractCode, billingOCC, fromDate, toDate).ToList()); }