In OpenOffice 3.2 and 3.3 mail merge printing, mail merge doesn't work if you restrict output using Range. However, restricting output using Selected Records works fine.
Here's how it works. Choose File > Print and click yes to print a form letter as usual. Then you have the option to print all records; to print selected records; or to print a range.
With the first two, everything works fine. But if you type in a range like records 1-3 to print, mailmerge just gives you blanks.
This isn't really a big issue since Selected Records works fine. But can cause problems if you don't know it and if like me you were just teaching an envelopes mail merge class. :) Luckily however I figured out the issue during break.