An error occurred.  Here is the response from Flickr:

<?xml version="1.0" encoding="utf-8" ?>
<rsp stat="fail">
	<err code="1" msg="User not found" />
</rsp>


And here is the response after passing through the parser:

array (
  'rsp' => 
  array (
    'err' => 
    array (
      'code' => '1',
      'msg' => 'User not found',
    ),
  ),
)