DoctrineExtensions: Root cannot be changed manually, change parent instead

This error drives me crazy! Sorry - I’m new with this.

My composer:

// composer.json
{
    "minimum-stability": "dev",
    "require": {
        "php": ">=5.3.3",
        "zendframework/zendframework": "2.2.2",
        "doctrine/doctrine-orm-module": "0.8.*@dev",
        "hounddog/doctrine-data-fixture-module": "dev-master",
        "zendframework/zftool": "dev-master",
        "gedmo/doctrine-extensions": "2.3.*",
        "phploc/phploc": "*",
        "phpmd/phpmd": "dev-master",
        "sebastian/phpcpd": "2.0.*@dev",
        "pdepend/pdepend" : "dev-master",
        "ruflin/elastica": "0.20.5.*@dev",
        "zendframework/zend-developer-tools": "dev-master"
    }
}

My setup:

zendframework/zendframework: 2.2.2
doctrine/annotations: dev-master (316b956)
doctrine/common: 2.4.x-dev (9a7e20e)
doctrine/doctrine-module: 0.8.0
doctrine/doctrine-orm-module: 0.8.0
doctrine/orm: dev-master (927d69b)
gedmo/doctrine-extensions: dev-master (ff48eb0)

Trying to make Nested Tree by documentation tutorial.

Error after this:

$food= new Category;
$food->setTitle('Food');
$em->persist($food);
$em->flush();

Gedmo\Exception\UnexpectedValueException: Root cannot be changed manually, change parent instead in /var/www/domains/zfb2.local/data/vendor/gedmo/doctrine-extensions/lib/Gedmo/Tree/Strategy/ORM/Nested.php on line 143

So I’ve added this for debug

var_dump($food);
object(Application\Entity\Category)[377]
  private 'id' => null
  private 'title' => string 'Food' (length=4)
  private 'lft' => null
  private 'lvl' => null
  private 'rgt' => null
  private 'root' => null
  private 'parent' => null
  private 'children' => null

and

// line #142 Nested.php
var_dump($config, $changeSet);

array (size=9)
  'strategy' => string 'nested' (length=6)
  'activate_locking' => boolean false
  'locking_timeout' => int 3
  'left' => string 'lft' (length=3)
  'level' => string 'lvl' (length=3)
  'right' => string 'rgt' (length=3)
  'root' => string 'root' (length=4)
  'parent' => string 'parent' (length=6)
  'useObjectClass' => string 'Application\Entity\Category' (length=27)

array (size=6)
  'title' => 
    array (size=2)
      0 => null
      1 => string 'Food' (length=4)
  'lft' => 
    array (size=2)
      0 => null
      1 => int 0
  'lvl' => 
    array (size=2)
      0 => null
      1 => int 0
  'rgt' => 
    array (size=2)
      0 => null
      1 => int 0
  'root' => 
    array (size=2)
      0 => null
      1 => int 0
  'parent' => 
    array (size=2)
      0 => null
      1 => null

So exception here

# Nested.php #143
        if (isset($config['root']) && isset($changeSet[$config['root']])) {
            throw new \Gedmo\Exception\UnexpectedValueException("Root cannot be changed manually, change parent instead");
        }

I can’t understand how to fix this.

Plz any help! Thx