Laravel transformer collection error

I'm using fractal in Laravel 5.2. I'm using a transformer on a collection like this:

public function allFromCompany()
{
    $users = UserModel::all();
    retu $this->response->collection($users, new UserTransformer);

}

UserTransformer

class UserTransformer extends FractalTransformerAbstract
{
    public function transform(UserModel $user)
    {
        retu [
            'user' => [
                'id'            => $user->id,
                'role'          =>
                    [
                        'role_id'       => $user->role_id,
                        'name'          => $user->role->name
                    ],
                'company'       =>
                    [
                        'company_id'    => $user->company_id,
                        'company'       => $user->company->name,
                    ],
                'active'        => $user->active,
                'name'          => $user->name,
                'lastname'      => $user->lastname,
                'address'       => $user->address,
                'zip'           => $user->zip,
                'email'         => $user->email
            ]
        ];
    }
}

But when I do it like that I receive an error:

{
  "status_code": 500,
  "debug": {
    "line": 10,
    "file": "/home/vagrant/Code/forum/app/Src/v1/User/UserTransformer.php",
    "class": "Symfony\Component\Debug\Exception\FatalThrowableError",
    "trace": [
      "#0 /home/vagrant/Code/forum/vendor/league/fractal/src/Scope.php(338): Src\v1\User\UserTransformer->transform(Object(Src\v1\User\User))",

When I try this with one item:

retu $this->response->item($user, new UserTransformer);

It works.