SQLSTATE[42S22]: Column not found: 1054 Unknown column 'b.title' in 'field list'

this is the my table creation .

CREATE TABLE billboard(id BIGINT AUTO_INCREMENT,title VARCHAR (255),country_id BIGINT,zone_id BIGINT,place VARCHAR(255),occassion VARCHAR(255),itinerary VARCHAR(255),created_at DATETIME NOT NULL,description TEXT NOT NULL,PRIMARY KEY(id)) ENGINE=INNODB;

public static function getInstance()

this is the my Doctrine Table

// public function getBillboardsForAUser($userId, $limit, $offset=0)
public function getBillboardsForAUser($userId,$limit,$offset=0)
{
$query = $this->createQuery('b')
->where('b.title=?',$title);
// ->where('b.owner_id = ?', $userId);
$followings = Doctrine::getTable('Follow')->getAllFollowing($userId);
foreach($followings as $following)

$query->orderBy('b.created_at DESC')
->limit($limit)
->offset($offset);
return $query->execute();

}

plz help me what is the problem.