3065 Expression #1 of ORDER BY clause is not in SELECT list, references column 'ibu42242_xcvx2w.xp.sort_order' which is not in SELECT list; this is incompatible with DISTINCT
in:
[select distinct p.products_id, p.products_image, pd.products_name from products_xsell xp, products p, products_description pd where xp.products_id = '15621' and xp.xsell_id = p.products_id and p.products_id = pd.products_id and pd.language_id = '1' and p.products_status = 1 order by xp.sort_order asc limit 6]