Cloudshare with PHP

Question

I am trying to get a simple search going but for lack of examples seem to be stuck... Can anyone tell me what might be wrong here? I am getting the following error and I am not sure why...

"/Guzzle/Service/Client.php:207: Fatal Error: Method call 'setState' is not allowed for a null value. "

My source:

<?php
     require 'aws-autoloader.php';
     use Aws\Common\Aws;
     use Aws\Common\Region;
     use Aws\CloudSearch\CloudSearchClient;
     use Aws\Common\Client\AbstractClient;
     use Aws\Common\Client\ClientBuilder;
     use Guzzle\Service\Resource\Model;

    $config = array(
        'key'    => '<key>',
        'secret' => '<secret>',
        'base_url' => 'search-<searchdomain>.us-west-1.cloudsearch.amazonaws.com',
        'region' => 'us-west-1'
      );

    $client = CloudSearchClient::factory($config);

    $domainClient = $client->getDomainClient('<searchdomain>', array(
        'credentials' => $client->getCredentials(),
    ));

    $result = $domainClient ->search(array('query' => 'foo'));
    $hitCount = $result->getPath('hits/found');
    echo "Number of Hits: {$hitCount}\n";
?>

I would appreciate any help... thank you.