title: Amazon MWS inventory XML feed doesn't update quantity
body: <p>I'm trying to upload my inventory to Amazon via XML feed, but my quantity in seller central doesn't update.</p>
  
  <p>My XML feed is below. Can anyone help find my mistake?</p>
  
  <pre><code>&lt;?xml version="1.0" ?&gt;&lt;AmazonEnvelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="amzn-envelope.xsd"&gt;
  &lt;Header&gt;
  &lt;DocumentVersion&gt;1.01&lt;/DocumentVersion&gt;
  &lt;MerchantIdentifier&gt;A3QPCC6I4V1QU3&lt;/MerchantIdentifier&gt;
  &lt;/Header&gt;
  &lt;MessageType&gt;Inventory&lt;/MessageType&gt;
  &lt;Message&gt;
  &lt;MessageID&gt;1&lt;/MessageID&gt;
  &lt;OperationType&gt;Update&lt;/OperationType&gt;
  &lt;Inventory&gt;
  &lt;SKU&gt;BHAL10105&lt;/SKU&gt;
  &lt;Quantity&gt;1&lt;/Quantity&gt;
  &lt;Available&gt;true&lt;/Available&gt;
  &lt;FulfillmentLatency&gt;7&lt;/FulfillmentLatency&gt;
  &lt;/Inventory&gt;
  &lt;/Message&gt;
  &lt;/AmazonEnvelope&gt;
  </code></pre>