Laravel 4.2无法使用Localization复数

I'm going to localize an application and I'm following strictly the simple constructs given by Laravel Localization system in http://laravel.com/docs/4.2/localization

My view has the following fragment:

@extends('layouts.base')

@section('content')
<h1>Processos</h1>
<table class="table table-bordered">
    <thead>
    <tr>
        <th rowspan="2">{{ Lang::choice('comuns.vicepresidencias', 10) }}</th>
    </tr>
    </thead>

In file app/lang/pt-BR/comuns.php I have

<?php

return array(
    'processos'        => 'Processo|Processos',
    'titulo'           => 'Título',
    'vicepresidencias' => 'Vice-presidência|Vice-presidências',
);

But, the result of {{ Lang::choice('comuns.vicepresidencias', 10) }} is not the plural form vice-presidências, but the single one vice-presidência.

I'm new to Laravel. So, any Laravel specialist could help me to solve that?