Join with composite keys in subsonic

Question

I'm trying to make a join on tables that have composite keys. Example:

var turnos = from turno in Turnos.All()  
             join turnoService in TurnoServices.All()  
                  on new {turno.pk1, turno.pk2} equals new {turnoService.pk1, turnoService.pk2 }  
             select turno;

The above sentence throws an exception:

"The construtor 'Void .ctor(System.Nullable1[System.Int16], System.Nullable1[System.Int32])' is not supported"

As I can see (debuging subsonic core 3.0.0.3) there is no implementation for join with composite keys, is that correct? I said that becouse in the method VisitNew from SubSonic.Linq.Structure.TSqlFormatter it only asks if the type of the constructor is DateTime and if not just throws an exception...

Thanks in advance.