Can't get TeX math to work

["Yang" <qn10q6w02 sneakemail com>]

Hi, I'm trying to use dia (0.96.1 on Ubuntu 7.10) to export to 
pstricks/tex, but my text (which are just tex math like $x$) doesn't get 
rendered as tex, and are shown literally as "$x$" in my resulting 
document. I tried on a minimal tex file:

\documentclass{article}
\usepackage{pstricks}
\begin{document}
\input{mixture}
\end{document}

Also, my resulting figure is huge. I found on the archives that you can 
use \resizebox, but does that also shrink the text/TeX?

Thanks,

Yang