current-menu-item at submenu pages

I use the twentytwelve navigation.

When i do submenus with pages, all subitems but only the pages have the class .current-menu-item. What do I wrong?

here is my current output:

<li id="menu-item-51" class="menu-item menu-item-type-post_type menu-item-object-page current-menu-item page_item page-item-2 current_page_item current-menu-ancestor current-menu-parent current_page_parent current_page_ancestor menu-item-51"><a href="https://ofroom.enabled.io/sample-page/">MATERIAL FüR DIE ZUKUNFT</a>
<ul class="sub-menu">
	<li id="menu-item-52" class="menu-item menu-item-type-post_type menu-item-object-page current-menu-item page_item page-item-2 current_page_item menu-item-52"><a href="https://ofroom.enabled.io/sample-page/">Votteler</a></li>
	<li id="menu-item-53" class="menu-item menu-item-type-post_type menu-item-object-page current-menu-item page_item page-item-2 current_page_item menu-item-53"><a href="https://ofroom.enabled.io/sample-page/">Interface</a></li>
	<li id="menu-item-54" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-54"><a href="https://www.tompeak.com">3M</a></li>
	<li id="menu-item-55" class="menu-item menu-item-type-post_type menu-item-object-page current-menu-item page_item page-item-2 current_page_item menu-item-55"><a href="https://ofroom.enabled.io/sample-page/">BASWA</a></li>
</ul>
</li>