Highlighting menu items when using new menu feature

Hi,
I am currently developing this website and wondered if anyone could help me with a small problem I have:

http://northstarcorporatefinance.com/

I am using multiple menus created using the new built in menu editor.

The problem I am having is the top menu loses its highlight when on a subpage e.g. the below where about us at the top should be highlighted:

http://northstarcorporatefinance.com/about/history/

All the subpages have the correct parent set up. I am really struggling with this so any help would be much appreciated.

Thanks and regards,
Chris