please help me out for this. I am trying long back to cancel Amazon order via MWS Feed API. But it is not canceling at all. Feed submission and all is successfully working, but the order is not canceling. Below is my Feed XML, We are using Report type both I tried: _POST_ORDER_ACKNOWLEDGEMENT_DATA_, _POST_FLAT_FILE_ORDER_ACKNOWLEDGEMENT_DATA_
<?xml version="1.0"?>
<AmazonEnvelope xmlns:xsi="http://www.w3.org/2001/XMLSchema instance"xsi:noNamespaceSchemaLocation="amzn-envelope.xsd">
<Header>
<DocumentVersion>1.01</DocumentVersion>
<MerchantIdentifier>My Store</MerchantIdentifier>
</Header>
<MessageType>OrderAcknowledgement</MessageType>
<Message>
<MessageID>1</MessageID>
<OrderAcknowledgement>
<AmazonOrderID>050-1234567-1234567</AmazonOrderID>
<StatusCode>Failure</StatusCode>
</OrderAcknowledgement>
</Message>
</AmazonEnvelope>