passing structures from C++ to ECLiPSe

Hello,
I would like to pass some data from C++ to eclipse and back, and
as a first experiment I created in C++ a list of ECLiPSe
structures (according to 3.1.5 in Embedding and interfacing manual) and
passed this list as an argument to an ECLiPSe predicate.

C++ code:
     ec_init();
     //compile ecl file with predicate printlist/1
     post_goal(term(EC_functor("compile",1),"eclipsecpp.ecl"));
     EC_resume();

     //create list
     EC_functor task("task",2);
     EC_refs T(3);
     char* names[3] = {"one","two","three"};
     int durations[3] = {1,2,3};

     for (int i=0; i<3; ++i)
     {
         T[i] = term(task,names[i],durations[i]);
     }
     EC_word tasklist = list(T);

     //call predicate printlist/1
     post_goal(term(EC_functor("printlist",1),tasklist));
     EC_resume();

eclipsecpp.ecl:
     printlist([]).
     printlist([H|T]) :- arg(1,H,N),writeln(N), printlist(T).

The execution of cpp program ends with error:
instantiation fault in arg(1, _1842, N)

But when I create the list in ECLiPSe
     tasklist([task("one",1),task("two",2),task("three",3)]).
and then execute query
     ?tasklist(T),printlist(T).
it works.

I don't know whether the structures created in C++ are
in ECLiPSe structures with field names or not, and i don't
know how to access them properly.
Can you tell me, what I'm doing wrong?

I use ECLiPSe 5.8/WinXP/VisualC++ .NET2003

Thanks in advance,
Jan Kelbel