Symfony2: InvalidArgumentException with Command folder

Question

I have a Symfony2 application. In one bundle, I have a command class inside a Command folder; then, when I try to execute:

php app/console doctrine:database:[something]

I get:

 [InvalidArgumentException]                                           
 There are no commands defined in the "doctrine:database" namespace. 

BUT, if I rename the Command folder (Command_ for example), the exception does not appear and all runs well, the problem is that I cannot use the command if the Command folder's name isn't 'Command'.

Here's may code:

RunMigrationXCommand.php:

<?php
#!/usr/bin/env php

// app/console
use Symfony\Component\Console\Application;
use eCommerce\MigrationBundle\Command\MigrationXCommand;


$application = new Application();
$application->add(new MigrationXCommand);
$application->run();

And MigrationXCommand.php:

class MigrationXCommand extends ContainerAwareCommand {

    protected function configure() {
        parent::configure();
        $this
                ->setName('migrationX')
                ->setDescription('Migration BBDD')
                ->addArgument(
                        'argument', InputArgument::OPTIONAL, 'What do you want to migrate?'
        );
    }

    protected function execute(InputInterface $input, OutputInterface $output) {
// ...
}

Any fix?