RayTracing, how to display my ray?

Hello,

I would like to display a ray I created,  I'm using

     ProMdl model;

    ProRay ray;

    ProError err;

    int    n_hits;

    ProSelection *p_sel;

     ProMdlCurrentGet(&model);

    ray.start_point[0] = 0.0;

    ray.start_point[1] = 0.0;

    ray.start_point[2] = 0.0;

    ray.dir_vector[0] = 1.0;

    ray.dir_vector[1] = 1.0;

    ray.dir_vector[2] = 1.0;

    ProGraphicsPenPosition( ray.start_point );

    ProGraphicsLineDraw( ray.dir_vector );

    ProWindowRefresh( -1 );

    err = ProSolidRayIntersectionCompute(model, 10.0, &ray, &p_sel, &n_hits);

I though this would be enough but apparently not...

Could you help please?

Thank you!

Emilie