OK, my final comment on this for a while, but hopefully one that will help generally.
Paul’s problem arose because the Server is making HTTP requests of itself in order to create the PDF.
So, if you have a blank newsletter (main one, not category one) you should issue the following http requests in your browser
This will return the RSS feed. If it’s blank it’s a problem with your RSS feed, play with the settings inside wordpress.
If, however, there is content in this feed but not in your newsletter then the problem is probably that when the server makes the request it is not getting back the same as you are getting in the browser. There are any number of reasons this could happen. Paul’s problem was that his http request was being redirected to a different virtual server because it was coming in via the wrong IP address.
The way to check this is to log onto the server and issue the commandline `wget http:///?feed=make-pdf-newspaper`
This will return a file, I think it is called index.html?feed=make-pdf-newspaper
It contains the feed that the server is retrieving. Open this file in an editor and you should see some clues as to what the problem is. Also look at the web server log file and see how the request is being logged. If it is going to the wrong virtual server, you need to change your server config to fix this.