在Php中安装SphinxQL

I followed all the steps in this guide, and have successfully installed Sphinx on my Ubuntu 14.04 server. However, I am not able to use SphinxQL (by Foolz) in my php pages. This is the code I am using :

<?php

use Foolz\SphinxQL\Connection;
use Foolz\SphinxQL\SphinxQL;

$conn = new Connection();
$conn->setParams(array('host' => 'localhost', 'port' => 9306));

$query = SphinxQL::create($conn)
->select('*')
->from('documents')
->match('desc', 'testing');


$result = $query->execute();

This gives me a "Fatal error: Class 'Foolz\SphinxQL\Connection' not found".

Sphinx is installed in the /etc/sphinxsearch/ directory.