Symfony form programatically submited doesn't update data

I created a from, and it seems its correct but the data is no t update wen is submitted

$form = $this->createForm($formType, $questionnaire)........//$questionnaire data is an array with the form data and the validation returns true$form->submit($questionnaire_data);    if ($form->isValid()) {

But when I check the database , questionnaire is not updated with the $questionnaire_data info

Do I missed something?