So, I'm having a problem mapping in fluent nhibernate. I want to use a join mapping to flatten an intermediate table: Here's my structure:

[Vehicle]
VehicleId
...

[DTVehicleValueRange]
VehicleId
DTVehicleValueRangeId
AverageValue
...

[DTValueRange]
DTVehicleValueRangeId
RangeMin
RangeMax
RangeValue

Note that DTValueRange does not have a VehicleID. I want to flatten DTVehicleValueRange into my Vehicle class. Tgis works fine for AverageValue, since it's just a plain value, but I can't seem to get a ValueRange collection to map correctly.

    public VehicleMap()
    {
        Id(x => x.Id, "VehicleId");
        Join("DTVehicleValueRange", x =>
        {
            x.Optional();
            x.KeyColumn("VehicleId");
            x.Map(y => y.AverageValue).ReadOnly();
            x.HasMany(y => y.ValueRanges).KeyColumn("DTVehicleValueRangeId"); // This Guy
        });
    }

The HasMany mapping doesn't seem to do anything if it's inside the Join. If it's outside the Join and I specify the table, it maps, but nhibernate tries to use the VehicleID, not the DTVehicleValueRangeId.

What am I doing wrong?