title: PHP cannot find a class
body: <p>Silly question, but I cannot figure out what's wrong. I have a ready to use script that prompts a fatal error when I run it.</p>
  
  <pre><code>use DDelivery\Order\DDeliveryOrder;
  use DDelivery\Order\DDeliveryProduct;
  use DDelivery\Order\DDStatusProvider;
  
  class IntegratorShop extends \DDelivery\Adapter\PluginFilters {
  ...
  </code></pre>
  
  <p>The error is:</p>
  
  <blockquote>
    <p>Fatal error: Class 'DDelivery\Adapter\PluginFilters' not found in
    .../ddelivery/IntegratorShop.php on
    line 40</p>
  </blockquote>
  
  <p>Frankly I never used 'use' declaration before, so it's hard to tell what's wrong. I'm sure it is something obvious. Thanks!</p>