CakePHP 3.5 saving into another table

I’m very new in cakephp 3.5 and I got problem with saving the data into different table. I have Question table and want to save the data into QuestionQuizzes table by using the checkbox function. When i try to submit the form, it got error saying 'The question could not be save".


public function existingQuestion()


$questions = $this->paginate($this->Questions);
$questionsQuiz = $this->QuestionsQuizzes->newEntity();


    $question = $this->QuestionsQuizzes->patchEntity($questionsQuiz, 

    if ($this->Questions->save($questionsQuiz)) {
        $this->Flash->success(__('The question has been saved.'));

        return $this->redirect(['action' => 'existingQuestion']);
    $this->Flash->error(__('The question could not be saved. Please, try again.'));


$this->set('_serialize', ['questions']);


I just need the checked data can be saved into the database table.