Rpad graphics

I'm not sure this is the appropriate forum--please let me know if I
should post somewhere else.

I have Rpad version 1.3.0 set up on my webserver. It works, except
that graphics are not displayed. They are created (i.e., when I run
the example I see that graphics files are created in
Rpad/server/xxxxxxxxx) but they don't appear on the web page.
Everything else seems to be working. Any help getting the graphics to
appear would be much appreciated. You can test the behavior at
http://prometheus.scp.rochester.edu/Rpad if you like.

Thanks,
-Ista