it looks like something is wrong with your printthread file (
http://www.setpro.com/forums/printthread.php?t=5875) ... right now it's showing a parse error--meaning you left something out
Make sure you are following directions found in the INSTRUCTIONS ... most "problems" that people have are because they try to do things in a rush ... place close attention to
REPLACE WITH and/or
ADD BELOW.
The printthread.php modification is ADD BELOW and will not work properly if you replace the existing code.