Add category to custom post type

Hello, I am having trouble to add the standard category taxonomy to my custom post type.

I can add custom made taxonomies to my custom post types.

I have the following cumstom post type:

register_post_type('people',
		array(	'label' => 'People',
				'public' => true,'show_ui' => true,
				'show_in_menu' => true,
				'capability_type' => 'post',
				'hierarchical' => false,
				'rewrite' => array('slug' => ''),
				'query_var' => true,
				'has_archive' => true,
				'supports' => array('title','editor','thumbnail',),
				'taxonomies' => array('category',),
				'menu_position' => 5,
				) );

in taxonomies I added category, but it is not working, what do I do wrong?

In my custom taxonomy I also have to add on which custom type it has effect on. Do I have to do this also with the standard category?