Class 'Predis\Client' not found in Laravel

I installed redis by

composer require  predis/predis

then I changed my config/queue.php like this:

'default' => env('QUEUE_DRIVER', 'redis'),

however when I try to use redis:

use Illuminate\Support\Facades\Redis;
Redis::connection();

I get this error :

FatalErrorException in Database.php line 63: Class 'Predis\Client' not found

What can be the problem? I use laravel 5.0

thanks,,

via Chebli Mohamed