Thanks laborg. Turns out my mac running leopard had Java 1.6 installed but it was set to run Java 1.5 by default. I had to change the order of the versions using "Java preferences" from the Utilities folder. Now it works! This page was very helpful:
http://www.javatester.org/version.html
Anyhow, as many people have undoubtedly told you, Briss is fantastic. Great idea superimposing all the even pages and odd pages against each other. Awesome!!