Algorithmic Combinatorics Publications

Got error 28 from storage engineQuery SELECT pp.abbrev as abbrev,a.activity_id,a.type_id,a.authors,a.title,a.booktitle,a.language,a.abstract,a.journal,a.series,a.volume,a.number,a.chapter,a.pages,a.publisher,a.address,a.isbn_issn,a.year,a.month,a.annote,a.note,a.editor,a.edition,a.translation,a.refereed,a.howpublished,a.organization,a.institution,a.keywords,a.sponsor,a.length,a.conferencename,a.activity,a.url,a.owner,a.webvisibility,a.type,au.risc_author,at.css_classname FROM activity_type at,activity a LEFT JOIN activity_risc_author_assignment au ON (a.activity_id=au.activity_id) LEFT JOIN activity_rg_assignment ag ON (a.activity_id=ag.activity_id) LEFT JOIN RiscPersonPublic pp ON au.risc_author=pp.abbrev WHERE a.type_id=at.type_id AND ag.rg_id='3' AND ag.webvisibility=1 AND (a.type_id='4' OR a.type_id='5' OR a.type_id='6' OR a.type_id='10' OR a.type_id='11' OR a.type_id='15' OR a.type_id='16' OR a.type_id='20' OR a.type_id='21' OR a.type_id='25') AND a.year='2018' GROUP BY a.activity_id ORDER BY a.year DESC,pp.lname,pp.fname ist ungültiges SQL.