Laravel 4 Queue - [InvalidArgumentException] There are no commands defined in the "queue" namespace

Laravel 4 Queue - [InvalidArgumentException] There are no commands defined
in the "queue" namespace

I'm using Laravel 4 + Beanstalk + Supervisor on a CentOS 6 VPS.
It was already a pain to install both beanstalk and supervisor on the VPS,
but I got through it (I have done this same installation on my local
server, a Macbook Pro, and it's working fine there).
I want to take advantage of Laravel 4's Queues and Beanstalk to send email
asynchronously. I have made a "program" for supervisor that basically runs
the command
php artisan queue:listen --env=production
but the process associated to that won't start succesfully. The log I
defined for this process outputs the following:
[InvalidArgumentException]
There are no commands defined in the "queue" namespace.
So apparently artisan is finding something that it doesn't like at all.
Please, please, PLEASE, would you help me? Only results I've found on
Google are an unanswered git issue post, and an equally useless thread
with no answers on Laravel's forums.