Facebook canvas app authorization works only in main page

Question

I have a Facebook canvas app.

I need an access token, the user authorizes the app and the apps main page works fine, but not the other pages. When I click one link in my app that redirects to subpage, it need authorization again.

my controller code (Yii) is:

protected function beforeAction($action)
{
    session_start();
    $this->fb = new Facebook\Facebook([
        'app_id' => '',
        'app_secret' => '',
        'default_graph_version' => 'v2.2',
    ]);
    $this->checkFbLogin();
    $this->getFbUser();

    if (!Yii::app()->player->uid) {
        $this->registerFbUser(); //connect facebook uid with game uid
    }

    return true;
}

private function checkFbLogin()
{
    $helper = $this->fb->getCanvasHelper();

    try {
        $accessToken = $helper->getAccessToken();
    } catch(Facebook\Exceptions\FacebookResponseException $e) {
        // When Graph returns an error
        echo 'Graph returned an error: ' . $e->getMessage();
        exit;
    } catch(Facebook\Exceptions\FacebookSDKException $e) {
        // When validation fails or other local issues
        echo 'Facebook SDK returned an error: ' . $e->getMessage();
        exit;
    }
    if (! isset($accessToken)) {
        //echo 'No OAuth data could be obtained from the signed request. User has not authorized your app yet.';
        echo '<script>top.window.location="' . $this->getLoginUrl() . '"; </script>';
        exit;
    }

    $this->accessToken = $accessToken;
}

private function getLoginUrl()
{
    $helper = $this->fb->getRedirectLoginHelper();
    $permissions = []; // optional
    $loginUrl = $helper->getLoginUrl('https://apps.facebook.com/my-game/', $permissions);
    return $loginUrl;
}

I can't see what is the problem. I can't find anything that can help. When I click a link in the app, I don't get my accessToken in the checkFbLogin() function.

I am using the PHP SDK v5.0.0 installed with composer.