working with liveconnect

Hello,

I'm working on a firefox extension that needs to use java classes and
requires communication both ways between java and ff.  So liveconnect
seems to be the way to go from what I'm reading.

However I'm trying to write just a very basic javascript file that
declares a java string (like in the tutorials) and it doesn't appear
to be running properly.  I'm pretty sure it is firefox and not my
javascript because I've run a number of liveconnect tests I've found
online and am getting inconsistent results.

For example I attempted the test found here: http://srp.stanford.edu/demo/
and it does not succeed.

neither does this test:
http://developer.apple.com/internet/safari/samples/ColorBlockApplet.html

I'm running Firefox 2.0.0.14 on a mac (perhaps this is a mac specific
problem?).  Is there any sort of setup procedure that I can do for
liveconnect - or should it work inherently in the browser?

thanks a lot,
pat