It's not the plugin, per say, but where you are putting it. You'll habe to put it in the folder under your system root which kinda looks like this:
C:/Documents and Settings/Administrator (or the account you're using)/My Documents/Maya/6.0/plugins
Maya is real touchy about where you put things.
Dave Baer
Professor of Digital Arts
Digital Media Arts College
Boca Raton, Florida
dbaer@dmac.edu