i have some problem about submit from for input value is not working.

[maxca]

$mink = new Mink(array(
'samarkpage' => new Session(new GoutteDriver(new GoutteClient())),
));
$mink->setDefaultSessionName('sessionName');
$mink->getSession('sessionName')->visit($startUrl);
$mink->getSession('sessionName')->getPage()->fillField('login', 'username');
$mink->getSession('sessionName')->getPage()->fillField('password', 'password');
$mink->getSession('samarkpage')->getPage()->find('css', '.loginButton')->submit();

URL : https://api.4shared.com/web/login?returnTo=https%3A%2F%2Fapi.4shared.com%2Fv1_2%2Foauth%2Fauthorize%3Foauth_token%3D0c2b0cfc1377a442ab4fca2c645df45a

Do you have a simple implement code like this ? .
What 's wrong ? .
Can you help me please.
Thank you.