LaTeX 中的咖啡渍

Question

我想在我非常重要的纸张上添加一些小咖啡渍，使用coffee4（http://hanno-rein.de/archives/349)。当我尝试让它工作时，我得到的是 PDF，但没有咖啡渍。实际上，我所做的只是处理 中未修改的文件coffee4.tar.gz。您能猜出哪里出了问题并指出正确的方向吗？

最小假定工作示例：

\documentclass{article}
\usepackage{tikz}
\usepackage{verbatim}
\usetikzlibrary{arrows,shapes}

\usepackage{coffee4}

\begin{document}
\title{LaTeX Coffee Stains}
\author{Hanno Rein\\
\texttt{http://hanno-rein.de}\\
Cambridge University}
\renewcommand{\today}{April 3, 2009}
\maketitle

\cofeAm{1}{1.0}{0}{5.5cm}{3cm}

\section{Introduction}
This package provides an essential feature to \LaTeX~that has been missing for too long. It adds a coffee stain to your documents. A lot of time can be saved by printing stains directly on the page rather than adding it manually. You can choose from four different stain types:
\begin{enumerate}
  \item $270^\circ$ circle stain with two tiny splashes 
  \item $60^\circ$ circle stain 
  \item two splashes with light colours
  \item and a colourful twin splash.
\end{enumerate}

\end{document}