[Plugin: Posts 2 Posts] Get conections in an archive page

Hi friends,
I need help with this. I miss something and I don´t know what is it.

This is my connection:

p2p_register_connection_type( array(
'name' => 'salas_conciertos',
'from' => 'sala',
'to' => 'concerts'
) );

On the “concerts” archive page, I´m trying to get the connected “sala” for each concert. I´m using this code:

// Find connected pages
$connected = new WP_Query( array(
'connected_type' => 'salas_conciertos',
'connected_items' => $post,
'nopaging' => true,
) );

// Display connected pages
while ( $connected->have_posts() ) : $connected->the_post();
the_title();
endwhile;

wp_reset_postdata(); // set $post back to original post

I get this error:
Warning: Could not find direction(s). in /usr/…/wp-content/plugins/posts-to-posts/core/query-post.php on line 16

What am I doing wrong??
Thanks!

http://ww.wp.xz.cn/extend/plugins/posts-to-posts/