The plugin just does not work.
I have wordpress installed as a sub-directory of the Joomla site - so both on the same server.
I have tried imported into the site which has no content - does not work.
I have tried importing into the wordpress site with all of the categories from the joomla site replicated on the joomla site - still does not work,
I've looked for a long time to find something that works - I thought this was it. Nope.