I have attempted to install a new font (source-sans-pro) onto my gentoo server, however when I run xelatex test.tex the PDF file it generates uses the font but does not give the expected output - i.e. the words "this is a test" show as the attached image:

The code I am using is as follows:
\documentclass[12pt]{article}
\usepackage{fontspec}
\setromanfont[Mapping=tex-text]{Source Sans Pro Light}
\begin{document}
This is a test.
\end{document}
Nothing ground breaking there - I'm wondering if perhaps the font has not been installed correctly, after a bit of googleing I found the following website - however following said instructions doesn't really give me anything other than the same result again..does anyone have any ideas? or even links to some documentation on how to install XeLaTeX fonts on gentoo correctly?
\usepackage[default,otf,light]{sourcesanspro}? – Silex Jan 23 at 15:02