You specified LaTeX, not pdfLaTeX... the script is mostly correct, except for the graphics file type. To be specific I need to know what graphics package you are using ... I'll assume "graphicx" here.
LaTeX will try to read the .png file as a post-script file.
It will look like one really long line - too long to be read.
http://theoval.sys.uea.ac.uk/~nlct/l...es/node43.html
AFAIK: unless you are using pdfLaTeX, you won't be able to include .png graphics in your documents using standard packages.
Convert the png file to eps. Use the GIMP.
Or you could use:
Code:
\DeclareGraphicsRule{.png}{eps}{.png}{.bb}{pngtopnm #1 | pnmtops}
\begin{figure}
[etc]
http://tex.loria.fr/english/prod-graph.html