Semantical Error Must be a StateFieldPathExpression

Question

[Semantical Error] line 0, col 75 near 'sesion sesion': 
     Error: Invalid PathExpression. Must be a StateFieldPathExpression. 

TopicsRepository class code:

class TopicsRepository extends EntityRepository {

    public function findAllTopics() {
        return $this->getEntityManager()
                        ->createQueryBuilder()
                        ->select('t.id,'
                                . 't.name,'
                                . 't.name stream_id,'
                                . 't.name admin_id,'
                                . 't.name instructor_id,'
                                . 't.sesion sesion'
                              )
                        ->from('FeedbackBundle:Topics', 't')
                        ->innerJoin('FeedbackBundle:Streams', 'sr', 'WITH', 't.stream = sr.id')
                        ->innerJoin('FeedbackBundle:Sessions', 'ss', 'WITH', 't.session = ss.id')
                        ->innerJoin('FeedbackBundle:Adminlogin', 'ad', 'WITH', 't.admin = ad.id')
                        ->innerJoin('FeedbackBundle:Instructors', 'i', 'WITH', 't.admin = i.id')
                        ->orderBy('t.id')
                        ->getQuery()
                        ->getResult();
    }

}


public function viewTopicAction(Request $request) {
        $viewtopic = $this->getDoctrine()
                ->getRepository('FeedbackBundle:Topics')
                ->findAllTopics();
        return $this->render('FeedbackBundle:Topic:view_topic.html.php', array('viewtopics' => $viewtopics));
    }

Must be a StateFieldPathExpression. What is the solution? i can not get any idea.