Nested Extension

Hi, I would like use this extension

https://github.com/creocoder/yii2-nested-sets and Create the Model of example and i gets error when i try create root category-menu


<?php

namespace frontend\models;


use common\models\Category;

use creocoder\nestedsets\NestedSetsBehavior;

use yii\db\ActiveRecord;


class Menu extends ActiveRecord

{


    public function behaviors()

    {

        return [

            'tree' => [

                'class' => NestedSetsBehavior::className(),

                 'treeAttribute' => 'tree',

                 'leftAttribute' => 'lft',

                 'rightAttribute' => 'rgt',

                 'depthAttribute' => 'depth',

            ],

        ];

    }


    public function transactions()

    {

        return [

            self::SCENARIO_DEFAULT => self::OP_ALL,

        ];

    }


    public static function find()

    {

        return new MenuQuery(get_called_class());

    }


   

}



I have table menu in Database whose i created through migration.

What is wrong?