与symfony和教义的关系问题

I have 3 entities, "Lecture", "Cource" and "CourseImage".

In class Lecture I have:

/**
 * @ORM\ManyToOne(targetEntity="Course", cascade={"persist"})
 * @ORM\JoinColumn(name="courseId", referencedColumnName="courseId")
 */
protected $course;

And in class Course I have:

/**
 * @ORM\OneToMany(targetEntity="CourseImage", mappedBy="course")
 */
protected $images;

All getters/setters are generated by symfony correctly.

I made a custom repository "LectureRepository" to retrieve some lectures with a native query where my code is:

public function findPopularByLocation($latitude, $longitude)
    $rsm = new ResultSetMapping();
    $rsm->addEntityResult('Acme\DemoBundle\Entity\Lecture', 'l');
    $rsm->addFieldResult('l', 'lectureId', 'lectureId');
    $rsm->addFieldResult('l', 'latitude', 'latitude');
    $rsm->addFieldResult('l', 'longitude', 'longitude');
    $rsm->addFieldResult('l', 'start', 'start');
    $rsm->addMetaResult('l', 'courseId', 'courseId', true);

    $sql = 'SELECT * , ( 3959 * ACOS( COS( RADIANS( ? ) ) * COS( RADIANS( latitude ) ) * COS( RADIANS( longitude ) - RADIANS( ? ) ) + SIN( RADIANS( ? ) ) * SIN( RADIANS( latitude ) ) ) ) AS distance FROM lectures HAVING distance < 25 ORDER BY distance LIMIT 0 , 20;';
    $query = $this->getEntityManager()->createNativeQuery($sql, $rsm);
    $query->setParameter(1, $latitude);
    $query->setParameter(2, $longitude);
    $query->setParameter(3, $latitude);
    return $query->getResult();
}

Finally in my controller I have this:

$popularLectures = $this
    ->getDoctrine()
    ->getManager()
    ->getRepository('AcmeDemoBundle:Lecture')
    ->findPopularByLocation($latitude, $longitude);

Which retrieves correctly my lectures, and I am able to also retrieve the course from the lecture:

$popularLectures[0]->getCourse();

But when I try:

$popularLectures[0]->getCourse()->getImages();

I get no results.. I suppose I should add something in the native query to make it retrieve images as well from the database, but I am not sure how and my research gave nothing back :( Any help will be appreciated!

EDIT: The getImages in Course is as follows.

/**
 * Get images
 *
 * @return \Doctrine\Common\Collections\Collection
 */
public function getImages()
{
    return $this->images;
}

Found the issue, I didn't have the inversedBy parameter in there..Thanks for the comments anyway.

/**
 * @ORM\ManyToOne(targetEntity="Course", inversedBy="images", cascade={"persist"})
 * @ORM\JoinColumn(name="courseId", referencedColumnName="courseId")
 */
protected $course;