implement NestedSetBehavior

I have problem when implement a NestedSetBehavior from incubator libraries. My Phalcon version is 1.3.3.

I create a folder "nested" that have 5 files (.htaccess, index.php, CategoriesController.php, Categories.php, and NestedSetBehavior.php). and i create categories table :

CREATE TABLE IF NOT EXISTS  `categories` (
    `id` int(11) NOT NULL,
    `lft` int(11) NOT NULL,
    `rgt` int(11) NOT NULL,
    `level` int(11) NOT NULL,
    `title` varchar(45) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

index.php file :

<?php
$loader=new \Phalcon\Loader();
$loader->registerDirs(array(__DIR__))->register();

$di = new \Phalcon\DI\FactoryDefault();
$di->set('db', function() {
    return new \Phalcon\Db\Adapter\Pdo\Mysql(array(
        "host" => "localhost",
        "username" => "root",
        "password" => "jacky^45",
        "dbname" => "dealer_acl"
    ));
});

$di->set('view', function() {
    return new \Phalcon\Mvc\View();
});

$app = new \Phalcon\Mvc\Application($di);
echo $app->handle()->getContent();

CategoriesController.php file :

<?php
class CategoriesController extends Phalcon\Mvc\Controller
{
    public function indexAction()
    {
        $category = new Categories();
        $category->title='Cars'; 
        $category->saveNode();
    }
}

Categories.php file :

<?php
class Categories extends Phalcon\Mvc\Model
{
    public $id;
    public $lft;
    public $rgt;
    public $level;
    public $title;

    public function initialize()
    {
        $this->addBehavior(new NestedSetBehavior(array(
            'leftAttribute' => 'lft',
            'rightAttribute' => 'rgt',
            'levelAttribute' => 'level'
        )));
    }
}

NestedSetBehavior.php i have copied from https://raw.githubusercontent.com/phalcon/incubator/master/Library/Phalcon/Mvc/Model/Behavior/NestedSet.php with any modification :

1. delete namespace on line 3
2. change nameclass from NestedSet to NestedSetBehavior
3. change the value of hasmanyRoots, from false to true private $hasManyRoots=true;

while i run https://localhost/nested/categories, get error message "There is no active transaction", but data inserted on database. So i try to add transaction code in controller:

public function indexAction()
{
    $trManager = new \Phalcon\Mvc\Model\Transaction\Manager();
    $tr = $trManager->get();

    $category = new Categories();
    $category->setTransaction($tr);
    $category->title='Laptop'; 
    $category->saveNode();
}

error message show "Fatal error: Call to a member function update() on a non-object in... on line 796". code in line 796 is : $owner::findFirst($pk)->update(array($this->rootAttribute => $pk));.

if i debug, $pk variable has a integer value. but operation of $owner::findFirst($pk) is failed to get a record. if i var_dump($owner::findFirst($pk)) get bool(false) result. So operation of update is getting fatal error.

I try another command, appendTo() and change my controller :

public function indexAction()
{
    $trManager = new \Phalcon\Mvc\Model\Transaction\Manager();
    $tr = $trManager->get();

    $root = new Categories();
    $root = $root->findFirst();

    $category= new Categories();
    $category->setTransaction($tr);
    $category->title='BMW';
    $category->appendTo($root);
}

error message show Query syntaxt error. if i debug query show like this "UPDATE categories SET lft=lft+2 WHERE lft>=2 AND root="

anyone can help me to implement NestedSetBehavior? Thanks.