Automapper missing map exception

gistfile1.txt

void Main()
{
	var profile = new MyProfile();

	Mapper.Initialize(cfg => cfg.AddProfile(profile));
}

public class MyProfile : Profile
{
	protected override void Configure()
	{
		CreateMap<Base, string>()
			.Include<Derived, string>()
			.ConvertUsing(src => src == null ? null : src.Value);
	}	
}

public class Base
{
	public string Value { get; set; }
}

public class Derived : Base
{
}