.current-menu-item class on custom post type children pages – again?

There is the situation.
I have created the custom post type – products withfuncionality like pages – I have to create hierarchy.

f.e:

1. Chairs:
   • Oak Chair
   • Nice Chair

The weird thing happens with wp_nav_menu(). When I open the first level page Chairs and display all the Chairs childrens in theme, the nav menu for the li item Products, gets the .current-menu-item class, but when I open the child page f.e. Oak Chair, the class disapears.

Why is that and how to set .current-menu-item class also when child page is opened?

This same problem happens again 🙁
WP Version 3.2.1

the ancestor-class .current-products-ancestor is not setted up 🙁