Sort list of posts (decending) by day of the week

Hi

I should sort a lsit of posts by a custom field “daynumber” repeating weekly.

I found this resolved post in this forum but get an error:
https://www.ads-software.com/support/topic/sort-list-of-posts-decending-by-day-of-the-week?replies=12

Here is what i have so far, thats exactly like the last answer:

<?php
function mam_posts_fields ($fields) {
   global $mam_global_fields;
   if ($mam_global_fields) $fields .= (preg_match('/^(\s+)?,/',$mam_global_fields)) ? $mam_global_fields : ", $mam_global_fields";
   return $fields;
}
function mam_posts_orderby ($orderby) {
   global $mam_global_orderby;
   if ($mam_global_orderby) $orderby = $mam_global_orderby;
   return $orderby;
}
add_filter('posts_fields','mam_posts_fields');
add_filter('posts_orderby','mam_posts_orderby');

$today = date('w') + 1;   // Day of week with 1 for Sunday
$tomorrow = ($today == 7) ? 1 : $today + 1;
$mam_global_fields = ", if(meta_value < $tomorrow, meta_value + 7, meta_value) as sortfield ";
$mam_global_orderby = " sortfield ASC";
$args = array(
  'post_type' => 'standort',
  'meta_key' => 'daynumber',
  'posts_per_page' => 5

);
query_posts($args);

?>

This works. Posts are sorted.
But I have 3 more query`s on the same page, and there is get the error.</strong>

WordPress database error: [Unknown column 'meta_value' in 'field list']
SELECT SQL_CALC_FOUND_ROWS phillswp_posts.*, if (meta_value < 7, meta_value + 7, meta_value) as sortfield FROM phillswp_posts INNER JOIN phillswp_term_relationships ON (phillswp_posts.ID = phillswp_term_relationships.object_id) WHERE 1=1 AND ( phillswp_term_relationships.term_taxonomy_id IN (1) ) AND phillswp_posts.post_type = 'post' AND (phillswp_posts.post_status = 'publish' OR phillswp_posts.post_status = 'private') GROUP BY phillswp_posts.ID ORDER BY sortfield ASC LIMIT 0, 1

Does anyone have a hint where this error cames from?
Thank you
Roman