Single sign on not logging user in

[eID Easy]

I am using single sign on

$command  = 'CreateSsoToken';
$postData = [
    'user_id' => $userid,
];

$result = localAPI($command, $postData);

User is redirected to the single sign on url and is redirected to the clientarea. However login cookie is not set and user is actually not logged in. What could be the problem?