PXSelectBase command with dynamic values in a delegate on a processing screen

I know I just asked a similar question recently, but I am still having an issue.  I really need to be able to use a dynamic value in the PXSelectBase command.

In this code, I am overriding a PXSelectBase command. (public delegate PXSelectBase GetShipmentsSelectCommandDelegate(SOShipmentFilter filter);)  One of my overrides works, but the one with the GroupBy / Having clause fails.

This one works.  Note that the And is pulling from the ICSProcShipPref.QtyLessThan field in my custom table. If I change the value in the table, the result set comes back as I would expect.  This allows me to use a dynamic amount to be selected based on the value in the table at run time (not have to use a constant).  

cmd = new
	SelectFrom<SOShipment>.
	InnerJoin<INSite>.On<SOShipment.FK.Site>.
	InnerJoin<Customer>.On<SOShipment.customerID.IsEqual<Customer.bAccountID>>.SingleTableOnly.
	InnerJoin<SOOrderShipment>.On<SOOrderShipment.shipmentNbr.IsEqual<SOShipment.shipmentNbr>>.SingleTableOnly.
	LeftJoin<Carrier>.On<SOShipment.FK.Carrier>.
	//LeftJoin<ICSProcShipPref>.On<SOShipment.FK.Carrier>.
	Where<
		SOShipment.confirmed.IsEqual<True>.
		And<Match<Customer, AccessInfo.userName.FromCurrent>>.
		And<Match<INSite, AccessInfo.userName.FromCurrent>>.
		And<Exists<
			SelectFrom<SOOrderShipment>.
			Where<
				SOOrderShipment.shipmentNbr.IsEqual<SOShipment.shipmentNbr>.
				And<SOOrderShipment.shipmentType.IsEqual<SOShipment.shipmentType>>.
				And<SOOrderShipment.invoiceNbr.IsNull>.
				And<SOOrderShipment.createARDoc.IsEqual<True>>>>>.
		And<SOOrderShipment.shipmentQty.IsLess<ICSProcShipPref.qtyLessThan.FromCurrent>>>.
	View(Base);
break;

In this statement, I am doing something very similar.  I am adding a join to the SOShipLine and SOLine tables to get a count of the lines in the SOLine table for the current shipment.

cmd = new
	SelectFrom<SOShipment>.
	InnerJoin<INSite>.On<SOShipment.FK.Site>.
	InnerJoin<Customer>.On<SOShipment.customerID.IsEqual<Customer.bAccountID>>.SingleTableOnly.
	InnerJoin<SOShipLine>.On<SOShipLine.shipmentNbr.IsEqual<SOShipment.shipmentNbr>>.
	InnerJoin<SOLine>.On<SOLine.orderNbr.IsEqual<SOShipLine.origOrderNbr>.
		And<SOLine.orderType.IsEqual<SOShipLine.origOrderType>>.
		And<SOLine.lineNbr.IsEqual<SOShipLine.origLineNbr>>>.
	LeftJoin<Carrier>.On<SOShipment.FK.Carrier>.
	//LeftJoin<ICSProcShipPref>.On<SOShipment.FK.Carrier>.
	Where<
		SOShipment.confirmed.IsEqual<True>.
		And<Match<Customer, AccessInfo.userName.FromCurrent>>.
		And<Match<INSite, AccessInfo.userName.FromCurrent>>.
		And<Exists<
			SelectFrom<SOOrderShipment>.
			Where<
				SOOrderShipment.shipmentNbr.IsEqual<SOShipment.shipmentNbr>.
				And<SOOrderShipment.shipmentType.IsEqual<SOShipment.shipmentType>>.
				And<SOOrderShipment.invoiceNbr.IsNull>.
				And<SOOrderShipment.createARDoc.IsEqual<True>>>>>>.
	AggregateTo<GroupBy<SOLine.orderNbr, Count<SOLine.orderNbr>>>.
	Having<Count.IsGreater<ICSProcShipPref.pickMedium.FromCurrent>>.
	//Having<Count.IsGreater<Ten>>.
	View(Base);

If I use Having<Count.IsGreater<Ten>>. it works.  This is hard coding 10 as a constant.

If I use Having<Count.IsGreater<ICSProcShipPref.pickMedium.FromCurrent>>. I get an error at run time.

I am able to use my custom table to pull the ICSProcShipPref.qtyLessThan.FromCurrent in the first example.  Why doesn’t it work in my Having clause when I try to do the same thing by pulling from ICSProcShipPref.pickMedium.FromCurrent?  

Just to be clear, if I use a constant Ten, it works fine.  

I’ve tried adding a Usr field (extension) to the filter and using that instead of my custom table, but I get the same error.

Here are the DAC fields.  I think they look perfect, but maybe I’ve been staring at this too long.

		#region QtyLessThan
		[PXDBDecimal()]
		[PXUIField(DisplayName = "Quantity Less Than")]
		public virtual Decimal? QtyLessThan { get; set; }
		public abstract class qtyLessThan : PX.Data.BQL.BqlDecimal.Field<qtyLessThan> { }
		#endregion

		#region PickMedium
		[PXDBInt]
		[PXUIField(DisplayName = "SO Line Count Greater Than")]
		public virtual int? PickMedium { get; set; }
		public abstract class pickMedium : PX.Data.BQL.BqlInt.Field<pickMedium> { }
		#endregion

This is baffling me.