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.
- 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.
- 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.