Error Request Laravel 5.1

I have an error that when using a request created by me and put required it throws me an error that it was not filled (it is a select that I bring data in ajax ), if I use the Request $request in my post method insert it without problems, here is my code:

UserController:

use Juanjo\Http\Requests\DetalleRequest;

public function asignacion(DetalleRequest $request)
    {   
        Detalle_Asignacion::create([
        'id_usuario'=>$request['id_usuario'],
        'id_datos_licencia'=>$request['tipos'],
            ]);
        Session::flash('message','Licencia Asignada Correctamente');
        return Redirect::to('/usuario');
    }

My View:

@extends('admin.layouts.admin')
    @section('content')
    <br/>
    @include('alerts.request')
    {!!Form::open(['route'=>'usuario.asignacion', 'method'=>'POST'])!!}

    <div class="row">
    <div class="col-md-6 col-md-offset-3">
    <div class="panel panel-primary">
                        <div class="panel-heading">
                           <h4> Asignar Licencias/Carnet's a <?php echo ucwords( $user->nombre.' '.$user->apellido)?></h4>
                        </div>
                        <div class="panel-body">
                        <div style="display:none">
                            {!!Form::text('id_usuario',$user->id,['class'=>'form-control'])!!}
                            </div>
                            <div class="form-group">
                                {!!Form::label('Licencia','Licencia/Carnet:')!!}
                                {!!Form::select('licencia',$licencias,null,['class'=>'form-control','id'=>'licencias','placeholder'=>'Selecciona una Licencia o Carnet'])!!}
                            </div>
                            <div class="form-group">
                            {!!Form::label('tipos','N°:')!!}
                            {!!Form::select('tipos',['placeholder'=>'Selecciona una opción'],null,['id'=>'tipos','class'=>'form-control', 'name'=>'tipos']) !!}
                            </div>
                        </div>
                        <div class="panel-footer">
                            {!!Form::submit('Registrar',['class'=>'btn btn-primary'])!!}
                        </div>
                    </div>
     </div>
     </div>     

    {!!Form::close()!!}

    {!!Html::script('intranet/js/jquery-2.1.0.min.js')!!}   
    {!!Html::script('intranet/js/select-dinamico.js')!!}
    @endsection

Routes:

Route::post('usuario/asignacion',['as' => 'usuario.asignacion', 'uses' => 'UsuarioController@asignacion']);