hello i cannot see any holed surface in your geometry if you play with Tools > Visibility > List browser you can easily see that or a view of the mesh shows it as well to define a holed surface you have to do Plane Surface(holed_surface_id) ={outer_loop_id, inner_loop_1_id, inner_loop_2_id, inner_loop_3_id, ....}; the inner loops must be inside the outer loop jean pierre aubry