Difficulties with autoload session

In my base controller under the line parent::initController($request, $response, $logger); I added this other:

$session = \Config\Services:ession($config)

However Im trying to use flash data in my login controller and Im getting the following error:
Call to a member function setFlashdata() on null

It looks that what I did was not enough to have session autoloaded in every controller. What am I missing?