I'm trying to do a basic authentication which considers email and password. My problem comes when I call the method Auth :: attempt I get the following error.

Model
class Usuario extends Eloquent{
protected $table = 'Usuario';
protected $primaryKey = 'idUsuario';
protected $fillable = array('Nombre',
'Apellido',
'TipoUsuario',
'Contrasena',
'Correo',
'Telefono');
}
Controller
class UsuarioController extends BaseController{
public function doLogin(){
$rules = array('correo' => 'required|email',
'contrasena' => 'required');
$validator = Validator::make(Input::all(), $rules);
if($validator->fails()){
return Redirect::to('usuario')
->withErrors($validator)// manda los errores al login
->withInput(Input::except('contrasena')); //
}else{
$userData = array(
'Correo' => Input::get('correo'),
'Contrasena' => Input::get('contrasena')
);
if(Auth::attempt($userData)){
echo 'bien';
}else{
return Redirect::to('login');
}
}
}
public function showLogin(){
return View::make('login');
}
}
Routte
Route::get('usuario', array('uses' => 'UsuarioController@showLogin'));
Route::post('usuario', array('uses' => 'UsuarioController@doLogin'));
Auth.php
return array(
'driver' => 'database',
'model' => 'User',
'table' => 'Usuario',
'reminder' => array(
'email' => 'emails.auth.reminder',
'table' => 'password_reminders',
'expire' => 60,
),
);