Main menu to stay highlighted when selecting submenu

Hi,

I have tried everything but is not working for me. I want the main menu (parent page) to stay highlighted when I select the submenu. I’ve edited the Page Attributes, adding the correspondent Parent page to each one of the Sub-pages I have listed in the submenu (I thought this was the problem). I am slso using this code

#access a:hover,
#access li.current_page_item > a,
#access li.current-menu-item > a {
background:#1B273F;
color:#fff;
text-decoration:none;}

Thanks