WebService Enpoint

Hello all 

I have made a custom Inquiry screen, that filters and provides a record based on passing 3 input parameter.

Now I want the same value to be returned when via WebService . I did extend  my webservice Endpoint and added new screen. However, I am not able to see the right value on mapped object 

When I call via my POSTMAN, I get empty result. 

Below is my code.

public class ItemSalesPrice : PXGraph<ItemSalesPrice>
    {


        public PXFilter<SalesPriceFilter> Filter;

        [PXFilterable]
        public PXSelect<SalesPriceResult> DetailsView;

        public PXCancel<SalesPriceFilter> Cancel;

        protected virtual IEnumerable<SalesPriceResult> detailsView()
        {
                 ----
                yield return ar;
            }
        }
}

    public class SalesPriceFilter : IBqlTable
    {
        #region CustomerID
        [PXDefault(PersistingCheck = PXPersistingCheck.Nothing)]
        [CustomerActive(DisplayName = "Customer ID", Required = true,IsKey =true)]
        public virtual int? CustomerID { get; set; }
        public abstract class customerID :
            PX.Data.BQL.BqlInt.Field<customerID>
        { }
        #endregion

        #region InventoryID
        [PXInt(IsKey = true)]
        [PXDefault(PersistingCheck = PXPersistingCheck.Nothing)]
        [PXUIField(DisplayName = "Inventory ID", Required = true)]
        [PXSelector(typeof(Search<InventoryItem.inventoryID>),
            typeof(InventoryItem.inventoryCD),
            typeof(InventoryItem.descr),           
            SubstituteKey = typeof(InventoryItem.inventoryCD))]
        public virtual int? InventoryID { get; set; }
        public abstract class inventoryID : PX.Data.BQL.BqlInt.Field<inventoryID> { }
        #endregion


        #region Uom
        [PXString(IsKey = true)]
        [PXDefault(PersistingCheck = PXPersistingCheck.Nothing)]
        [PXUIField(DisplayName = "UOM", Required = true)]
        [PXSelector(typeof(Search<INUnit.fromUnit>),
            typeof(INUnit.fromUnit),          
            SubstituteKey = typeof(INUnit.fromUnit))]
        public virtual string Uom { get; set; }
        public abstract class uom : PX.Data.BQL.BqlString.Field<uom> { }
        #endregion

    }

    public class SalesPriceResult : IBqlTable
    {
        #region UsrInventoryID
        [PXString]
        [PXUIField(DisplayName = "Inventory ID", IsReadOnly = true)]
        public virtual string UsrInventoryID { get; set; }
        public abstract class usrInventoryID : PX.Data.BQL.BqlString.Field<usrInventoryID> { }
        #endregion

        #region UsrCustomerID
        [PXString]
        [PXUIField(DisplayName = "Customer ID", IsReadOnly = true)]
        public virtual string UsrCustomerID { get; set; }
        public abstract class usrCustomerID : PX.Data.BQL.BqlString.Field<usrCustomerID> { }
        #endregion

        #region UsrSalesPrice
        [PXDecimal(6)]
        [PXUIField(DisplayName = "Sales Price", IsReadOnly = true)]
        public virtual Decimal? UsrSalesPrice { get; set; }
        public abstract class usrSalesPrice : PX.Data.BQL.BqlDecimal.Field<usrSalesPrice> { }
        #endregion

        #region UsrSalesPrice
        [PXString()]
        [PXUIField(DisplayName = "Unit of Measure", IsReadOnly = true)]
        public virtual string UsrUom { get; set; }
        public abstract class usruom : PX.Data.BQL.BqlString.Field<usruom> { }
        #endregion
    }

Could anyone suggest on how can I add my input parameter on mapped Object.

Appreciate help. Thank you.