Problem z QueryBuilder pobieranie danych z dwóch kolumn. Symfony2.

Mam problem z uzyskaniem danych z dwóch tabeli mianowicie:
Chce uzyskać coś co w SQL wygląda następująco:

SELECT SUM(TableA.sum) AS Suma, TableB.name FROM TableA INNER JOIN TableB ON TableA.category_id = TableB.id GROUP BY TableB.name

Klasa Expenditure:

/**
 * Expenditure
 *
 * @ORM\Table(name="accountant_expenditure")
 * @ORM\Entity(repositoryClass="accountant\ExpenditureBundle\Repository\ExpenditureRepository")
 */
class Expenditure
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @ORM\ManyToOne(targetEntity="accountant\UserBundle\Entity\User")
     * @ORM\JoinColumn(name="create_by_user_id", referencedColumnName="id", onDelete="CASCADE")
     */
    private $createBy;

    /**
     * @var \DateTime
     *
     * @ORM\Column(name="create_at", type="datetime")
     */
    private $createAt;

    /**
     * @var integer
     *
     * @ORM\ManyToOne(targetEntity="accountant\ExpenditureBundle\Entity\ExpenditureCategories")
     * @ORM\JoinColumn(name="category_id", referencedColumnName="id", onDelete="CASCADE")
     */
    private $category;

    /**
     * @var float
     *
     * @ORM\Column(name="sum", type="float")
     */
    private $sum;
//...

Klasa ExpenditureCategory:

/**
 * ExpenditureCategories
 *
 * @ORM\Table()
 * @ORM\Entity(repositoryClass="accountant\ExpenditureBundle\Repository\ExpenditureCategoriesRepository")
 */
class ExpenditureCategories
{
    /**
     * @var integer
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @var string
     *
     * @ORM\Column(name="name", type="string", length=255)
     */
    private $name;
//...

Klasa ExpenditureRepository:

 public function findCurrentMonthExpendituresSumByCategory()
    {
        $firstDay = new \DateTime('first day of this month');
        $lastDay = new \DateTime('last day of this month');

        return $this->createQueryBuilder('e', 'c')
            ->select('SUM(e.sum) AS TOTAL, c.name')
            ->leftJoin('s.category', 'c')
            ->where('s.createAt BETWEEN :start AND :end')
            ->setParameter('start', $firstDay->format('Y-m-d'))
            ->setParameter('end', $lastDay->format('Y-m-d'))
            ->groupBy('c.name')
            ->getQuery()
            ->getResult();
    }

Błąd:

[Semantical Error] line 0, col 101 near '.category c WHERE': Error: Identification Variable s used in join path expression but was not defined before.

Proszę o pomoc, być może mam coś źle z relacjami w adnotacjach? Nie mam już pojęcia.

Problem rozwiązany, zostawię to tu jakby ktoś potrzebował:

 public function findCurrentMonthExpendituresSumByCategory()
    {
        $firstDay = new \DateTime('first day of this month');
        $lastDay = new \DateTime('last day of this month');

        return $this->createQueryBuilder('e')
            ->select('SUM(e.sum) AS TOTAL, c.name')
            ->leftJoin('e.category', 'c')
            ->where('e.createAt BETWEEN :start AND :end')
            ->setParameter('start', $firstDay->format('Y-m-d'))
            ->setParameter('end', $lastDay->format('Y-m-d'))
            ->groupBy('c.name')
            ->getQuery()
            ->getResult();
    }