Cannot subscribe a node that has been published

Openfire Plugins
1
  1. i’ve create a node from the server by user ‘u1@myserver’:
           <pubsub xmlns='[http://jabber.org/protocol/pubsub](http://jabber.org/protocol/pubsub)'>

and the server responses:

2.the,i changed to user ‘u2@myserver’ to subscribe the node i’ve been created:

           <pubsub xmlns='[http://jabber.org/protocol/pubsub](http://jabber.org/protocol/pubsub)'>

but the server response with an error ‘404’:

<error code='404’type=‘cancel’>

can anyone explain where the problem is , thx so much