The Pixie package seem to provide pre-compiled shaders which have been generated by an older version of Pixie, causing 'rdnr' to fail to read them and throwing errors like:
/sphere.rib (10): Error in shader "/opt/pixie/shaders/ambientlight.sdr"
(0) ("syntax error") (v2.2.6)
./sphere.rib (10): Failed to find shader "ambientlight"
(as just reported by someone else on SF: https://sourceforge.net/tracker/?func=detail&aid=2853866&group_id=59462&atid=491092 )
a good way to fix this behaviour is to provide a Makefile that can regenerate the shaders using the newer version of Pixie; attached there is a makefile that is officially used by the Gentoo distro (see http://bugs.gentoo.org/show_bug.cgi?id=286126 ) to correctly re-generate all the shaders before to install them; feel free to include the proposed makefile into the main Makefile workflow of the project.
Hope to be useful.