Doctrine GeneratedValue(strategy="AUTO")不起作用

我使用的学说与symfony2和sqlite数据库，我有插入值的问题，因为id不再增加了。我只是改变了一个字段注释，我已经删除了数据库，并重新创建了它:

php app/console doctrine:database:create --env=dev
php app/console doctrine:schema:update --force

反应:

Database schema updated successfully! "4" queries were executed

我已经做了第二次更新，我有

Database schema updated successfully! "14" queries were executed

我有一个类Post:

namespace Llafon'BlogBundle'Entity;
use Doctrine'ORM'Mapping as ORM;
/**
 * @ORM'Table(name="post")
 * @ORM'Entity
 */
class Post {
    /**
     * @ORM'Column(type="integer")
     * @ORM'Id
     * @ORM'GeneratedValue(strategy="IDENTITY") //I also tried "AUTO"
     */
    protected $id;
    /**
     * @ORM'Column(type="string", length=100, nullable=false)
     */
    protected $title;
    /**
     * @ORM'Column(type="text", nullable=false)
     */
    protected $content;
    /**
     * @ORM'Column(type="datetime", nullable=false)
     */
    protected $date;   
    /**
     * @ORM'ManyToOne(targetEntity="User") //This variable was an integer before
     * @ORM'JoinColumn(name="id", referencedColumnName="id")
     */
    protected $author;
    /**
     * @ORM'Column(type="string", nullable=false)
     */
    protected $image_name;
    public function __construct() {
        $this->date = new 'DateTime();
    }

插入:

    public function addAction(Request $request) {        
        $post = new Post();
        $user = $this->container->get('security.context')->getToken()->getUser();
        $post->setAuthor($user); //$user is not null
        $post->setContent("zz");
        $post->setImageName("aaa");
        $post->setTitle("fff");
        $em = $this->getDoctrine()->getManager();
        $em->persist($post);
        $em->flush();die();
}

An exception occurred while executing 'INSERT INTO post (title, content, date, image_name, id) VALUES (?, ?, ?, ?, ?)' with params ["fff", "zz", "2015-10-25 21:45:37", "aaa", 1]:
SQLSTATE[23000]: Integrity constraint violation: 19 UNIQUE constraint failed: post.id

所以我们可以看到这里的自动递增没有工作(id应该是'2')。

我还清除了symfony缓存，但它没有改变任何东西。

但是，如果我将$author类型更改为整数(而不是join)，则自动增量工作。

提前感谢您的帮助。