publish an item with no ItemId

According to XEP-0060 7.1.2, When you try to publish an item to the publish server:

7.1.2 Success Case

If the pubsub service can successfully process the request, it MUST inform the publisher of success. If the publish request did not include an ItemID, the IQ-result SHOULD include an empty <item/> element that specifies the ItemID of the published item.

Example 100. Service replies with success

<iqtype='result'
    from='pubsub.shakespeare.lit'
    to='hamlet@denmark.lit/blogbot'
    id='publish1'>
  <pubsubxmlns='http://jabber.org/protocol/pubsub'>
    <publishnode='princely_musings'>
      <itemid='ae890ac52d0df67ed7cfdf51b644e901'/>
    </publish>
  </pubsub>
</iq>
      

However when I tried to publish an item with no ItemID, I only get an IQ-Result without the pubsub element. Could somebody let me know if I did something wrong or Openfire is doing something differently from the XEP-0060?

Thanks