Include selected taxonomy ID in loop (from shortcode)

Hello everyone,
I would like to include only selected taxonomies ID in my loop (via shortcode), but can’t achieve it. I do not know what I’m doing wrong.

This is my shortcode code (not working):

add_shortcode( 'myshrt', 'my_shortcode' );
function my_shortcode( $atts ) {

extract(shortcode_atts(array(
      'posts' => -1,
      'include' => '',
   ), $atts));

$args = array(
	'post_type' => 'my_custom_post_type',
	'showposts' => $posts,
	'orderby' => 'date',
	'order' => 'DESC',
              'tax_query' => array(
                        array(
                       'taxonomy' => 'my_custom_tax',
                        'field' => 'id',
	                'terms' => array( $include )
                         )
              ),

);
$mynewquery = new WP_Query( $args );

?>

<?php if ( $mynewquery->have_posts() ) : while ( $mynewquery->have_posts() ) : $mynewquery->the_post(); ?>

<h2><?php the_title(); ?><h2/>
<?php endwhile; else: ?>
<?php endif; ?>
<?php wp_reset_query(); ?>

}

I put shortcode like this:
[myshrt posts="5" include="40,50"]

But without effect.
Can anybody help ?