title: Amazon itemLookup not returning new and used count
body: <p>I'm hitting the Amazon Product API with this function:</p>
  
  <pre><code>public function itemLookup($id, $responseGroup = 'OfferFull,Images,BrowseNodes,ItemAttributes,Offers'){
  
      $parameters = array(
      "IdType" =&gt; "ASIN",
      "Operation" =&gt; "ItemLookup",
      "ItemId" =&gt; $id,
      "ResponseGroup" =&gt; $responseGroup,
      "Condition" =&gt; "Used"
      );
  
      $signedUrl = $this-&gt;getSignedUrl($parameters);
  
      //return XML to front end
      return $productId = simplexml_load_file($signedUrl);
   }
  </code></pre>
  
  <p>It works and returns the XML document.</p>
  
  <p>However, it doesn't return anything in the:</p>
  
  <pre><code>&lt;OfferSummary&gt;
      &lt;TotalNew&gt;0&lt;/TotalNew&gt;
      &lt;TotalUsed&gt;0&lt;/TotalUsed&gt;
      &lt;TotalCollectible&gt;0&lt;/TotalCollectible&gt;
      &lt;TotalRefurbished&gt;0&lt;/TotalRefurbished&gt;
  &lt;/OfferSummary&gt;
  &lt;Offers&gt;
      &lt;TotalOffers&gt;0&lt;/TotalOffers&gt;
      &lt;TotalOfferPages&gt;0&lt;/TotalOfferPages&gt;
      &lt;MoreOffersUrl&gt;0&lt;/MoreOffersUrl&gt;
  &lt;/Offers&gt;
  </code></pre>
  
  <p>In this particular example, I can visit the product URL and see there are new and used products available.</p>
  
  <p>It seems the API chokes when the item has multiple colors/sizes/options.</p>
  
  <p>Anyone have any idea how I can get around this?</p>