Returning Aggregate

I'm learning how to build aggregates query. The following code works fine and generate a well builded query but I have a problem with returned values in results : for all the lines , I have line.NumTraitement = null line.NumBloc = null line.PoidsNet = 0

Where I am wrong ?

LightSpeedContext<LightSpeedModel1UnitOfWork> context = new LightSpeedContext<LightSpeedModel1UnitOfWork>("Development"); 
struct myGroupingResult
{
    public string NumTraitement { get; set; }
    public string NumBloc { get; set; }
    public decimal PoidsNet { get; set; }
}

         using (var unitOfWork = context.CreateUnitOfWork())
        {

            var query = new Query(typeof(Pesee));
            query.Group = Group.By("NumTraitement").AndBy("NumBloc");                

            query.Projection.Add("NumTraitement");
            query.Projection.Add("NumBloc");
            query.Projection.Add(Entity.Attribute("PoidsNet").Function("SUM"));

            var results = unitOfWork.Project<myGroupingResult>(query);

            foreach (myGroupingResult line in results)
            {

            }

        }

This sounds like an issue - can you send us through a small repro project please and we can investigate this.

Jeremy