Controller:
 $model = new GalleryAlbum;
                $model->user_id = 1;
                $model->secret=1;
                $model->root=0;
                $model->level=0;
                $model->saveNode();
                var_dump($model->getErrors());
################

MODEL:

  public function behaviors() {
        return array(
            'NestedSetBehavior' => array(
                'class' => 'ext.behaviors.trees.NestedSetBehavior',
                'leftAttribute' => 'lft',
                'rightAttribute' => 'rgt',
                'levelAttribute' => 'level',
                'hasManyRoots'=>true,
                ));
    }