L5 session put not working

hi,

I dont get why I cant create a session variable using this code :

public function commitTransaction($cluster,$transId)
{
    try {
        $response = $this->client->request('PUT', 'https://' . $cluster . '/' . $transId, [
            'auth' => ['id', 'pass'],
            'proxy' => '',
            'verify' => false,
            'json' => [
                'state' => 'VALIDATING'
            ]
        ]);
    $res = $response->getBody()->getContents();
    session()->put('commit',$res);
    }
    catch (RequestException $e){
        var_dump($e->getResponse()->getBody()->getContents());

    }
 }

Thanks for your help.