wp_query with multiple custom post type is not working

Hello all, i have this simple code:

$blog = new WP_Query( array(
	'post_type' => array( 'eventi' , 'locali' ),
	'posts_per_page' => 6 ,
	'post__not_in' => get_option( 'sticky_posts' ),
	'paged' => $paged
	)
);

Of course i declared both ‘eventi’ and ‘locali’ post types. In fact, if i use one of them, the loop works fine. But if use both of them, no posts are showed. Even if i use just this other code:

$blog = new WP_Query( array(
	'post_type' => array( 'eventi' , 'locali' ),
	)
);

No posts are showed. What should i do? Thanks!!! 🙂