Gallery don't show anything

Hi, i try to setup my gallery. But in all cases there are no images visible. I run the theme on an WP network installation. Here what i do. - Add an new gallery via "Add New" - I add Images via Media and create gallery The image at self are visible via attachment but not in the gallery. Gallery: http://heiko-schoor.com/gallery/meine-galerie/ Shortcode in the Gallery: [gallery ids="150,149,148"] Attachement 150: http://heiko-schoor.com/?attachment_id=150 What i am doing wrong?