Version 4.2.1.0 : Problem with ProjectTo

I am using AutoMapper 4.2.1.0 to map an entity type into a DTO using ProjectTo .

I have created my Map like this :

var config = new MapperConfiguration(cfg =>
            {
                cfg.CreateMap<Order, OrderDTO>();
                cfg.CreateMap<Order_Detail, Order_DetailDTO>();
            });

and I am using config object like this :

var builder = config.ExpressionBuilder;
return ((IQueryable<Order>) property.GetValue(_db, null)).ProjectTo<OrderDTO>(builder);

but I am getting an error that says :

Missing map from Order to OrderDTO. Create using Mapper.CreateMap<Order, OrderDTO>.

Is there something that I do wrong ?

Here is the same question that I asked on SO: http://stackoverflow.com/questions/36450885/automapper-doesnt-work-as-it-should

[TylerCarlson1]

var ((IQueryable<TEntity>) property.GetValue(_db, null)).ProjectTo<TDto>(config); should work

[Beatles1692]

I was misled by this article : https://lostechies.com/jimmybogard/2016/01/21/removing-the-static-api-from-automapper/