posts_per_page – custom page!

i have a problem with the ‘posts_per_page’- no matter that i set it to, e.g 10 or -1, it always only show one post!

<?php $loop = new WP_Query( array( ‘post_type’ => ‘producenter’, ‘posts_per_page’ => 0, ‘orderby’ => ‘rand’, ‘post__not_in’ => array($post->ID) ) ); ?>
<p class=”loop__title”>Andre leverand?rer:</p>
<ul class=”grid__content small”>
<?php while ( $loop->have_posts() ) : $loop->the_post(); ?>

• 
  <?php the_post_thumbnail(); ?>
  <h4><?php the_title(); ?></h4>
  <?php if( get_field( “deloverskrift” ) ): ?>
  <p><?php the_field( “deloverskrift” ); ?></p>
  <?php endif; ?>
  

<?php endwhile; ?>