Did you follow the install instructions at the sun website? I did and found two things that were not clear.
One, it says to 'export the NPX_PLUGIN_PATH'. I did and, sure enough, $ env showed that this path was in effect. However,
Two, export only works for the current session so, after a reboot, the path was no longer in effect. Well, I figured to add the export-PATH line to the bottom of my ~/.bash_profile and it gets set at boot but, OK,
Three, this wiped out the path to my other netscape plugins, so I added that path to the line in .bash_profile:
Suggest you take another look at sun's install directions and, maybe, try something like what I did.