stats_get_csv retrieve just a few posts (not the one I set in "limit" parameter)

This code pulls the top viewed posts (via wordpress stats API). I can set how many posts to show and the days to “count”:

<?php
        if ( function_exists('stats_get_csv') && $top_posts = stats_get_csv( 'postviews', "days=60&limit=15")) {
        echo '<ol class="most-viewed">';
          foreach ( $top_posts as $post ) {
            if (
			$post['post_id']
			&& get_post( $post['post_id'] )
			&& 'post' === get_post_type( $post['post_id'] )
			)
              echo '<li><a href="' . get_permalink( $post['post_id'] ) . '">' .
                  get_the_title( $post['post_id'] ) . '</a> (' . number_format_i18n( $post['views']) .' visite)</li>';
          }
          echo '</ol>';
        }
?>

The strange thing is that if I set days=2&limit=10 I get 6 posts (instead of 10), if I set days=60&limit=10 I get 2 posts, if I set days=-1&limit=10 I get just 1 post!!! Why does this happen? 🙁 The blog has about 2000 articles so there are of course more than 10 posts. 😀

Why doesn’t it just pull always 10 posts?

Thanks in advance!