Why doesn't the PDF button work?

From Joomla! Documentation

In Joomla! version 1.5, there are two known issues with using the PDF button to view articles in PDF format.

  1. With Internet Explorer, pressing this button produces a blank screen. You can work around this if you right-click on the button and select "Open Link", "Open Link in New Tab", or "Open Link in New Window". The button works correctly in Firefox.
  2. With both Internet Explorer and Firefox, some articles don't format correctly.

These issues are being worked on and should be corrected in a future Joomla! release.