hasManyToMany save again

3 tables, 3 models: Sections, Lectures, SectionsHasLectures Relation is saved, Section is saved, Lectures is updated and set all values to NULL. What am I doing wrong? Thank you.

<?php
    class Sections extends Model  {
      public function beforeValidationOnCreate()
      {
          // Timestamp the confirmaton
          $this->publishdon = time();
      }

      public function initialize()
      {
          $this->hasManyToMany(
              "id",
              "Models\SectionsHasLectures",
              "sectionId", "lectureId",
              "Models\Lectures",
              "id",
              ['alias' => 'lectures']
          );
      }

<?php
    class Lectures extends Model  {
      public function beforeValidationOnCreate()
      {
          // Timestamp the confirmaton
          $this->publishdon = time();
      }

      public function initialize()
      {
          $this->useDynamicUpdate(true); 

          $this->hasManyToMany(
              "id",
              "Models\SectionsHasLectures",
              "sectionId",
              "lectureId",
              "Models\Sections",
              "id",
              ['alias' => 'sections']
          );

      }

<?php
    class SectionsHasLectures extends Model  {

      public $id;
      public $sectionId;
      public $lectureId;
      public $created;
      public $modified;

      public function beforeValidationOnCreate()
      {
          $this->created = time();
      }

      public function initialize()
      {
          $this->belongsTo('sectionId', 'Models\Sections', 'id', array(
              'alias' => 'section'
          ));
          $this->belongsTo('lectureId', 'Models\Lectures', 'id', array(
              'alias' => 'lecture'
          ));
      }

Try to keep with the existing Lectures (in the form select the existing lectures):

<?php
    $section = new Sections();
    $lectures = $this->request->getPost('lectures');
    $_lectures = array();
    Lectures::setup(array('notNullValidations' => false));
    foreach ($lectures as $lectureId) {
      $lecture = new Lectures();
      $lecture->id = $lectureId;
      $_lectures[] = $lecture;
    }

    $section->assign(array(
      'title' => $this->request->getPost('title', 'striptags'),
      'speakerId' => $this->request->getPost('speakerId', 'int'),
      'desc' => $this->request->getPost('desc'),
      'published' => $published,
      'pubDate' => strtotime($this->request->getPost('pubDate')),
      'unpubDate' => strtotime($this->request->getPost('unpubDate')),
    ));

    if (!$section->save()) {
      foreach ($section->getMessages() as $message) {
        $this->flashSession->error($message);
      }
    } else {
      $section->lectures = $_lectures;
      $section->update(); 
      $this->flashSession->success("Секция успешно добавлена");
    }