Database Problem

Unknown column 'Article.title' in 'field list'
SELECT Article.id, Article.title, Article.imgurl, Article.summary, Article.plot, Article.newsfrom, DM_menu.id as rub, DM_menu.name as category, Article.pubdate, Article.imgcopy FROM Article LEFT JOIN DM_news_cat ON DM_news_cat.id_news=Article.id JOIN DM_menu ON DM_menu.`id`=DM_news_cat.id_cat WHERE online=1 GROUP BY DM_news_cat.id_news ORDER BY Article.pubdate DESC, Article.id DESC LIMIT 20, 20