De query: 'SELECT (SELECT COUNT(*) FROM `pcms_module_enq_bezoeker` WHERE status = 1) as totaal, (SUM(cijfer) / COUNT(*)) AS eindcijfer FROM `pcms_module_enq_bezoeker_antwoord` ba JOIN `pcms_module_enq_bezoeker` b ON b.id = ba.bezoeker_id JOIN `pcms_module_enq_antwoord` a ON a.id = ba.antwoord_id JOIN `pcms_module_enq_vraag` v ON v.id = a.vraag_id JOIN `pcms_module_enq_categorie` c ON c.id = v.categorie_id WHERE cijfer != 0 AND formulier_id = 2 GROUP BY b.id' is mislukt