Why does my LaTeX subfigure not work with an a0poster?

Question

Here's my problem. I have a bunch of figures already written in a LaTeX document, and I'd like to reuse them for a poster. The code for the figure looks like:

\begin{figure}[htp]
  \begin{center}  
    \subfigure[Figure A]{\label{fig:Sample-a}\includegraphics[scale=5]{Image1.png}} 
    \subfigure[Figure B]{\label{fig:Sampple-b}\includegraphics[scale=5]{Image2.png}} 
  \end{center}
  \caption{This is my caption!}
\label{LineJustification}
\end{figure}

And it works when I put at the beginning:

\usepackage{subfigure}
\usepackage{graphicx}

When I'm putting together the poster, I'm using the template I've found online at this website, with packages like:

\documentclass[a0]{a0poster}
\pagestyle{empty}
\setcounter{secnumdepth}{0}
\usepackage[absolute]{textpos}
\usepackage[it]{subfigure}

(and I've commented out the graphics, wrapfig, and times packages from the landscape file, just in case they're interfering).

So what gives? Why do I get the following error when I try to put the same figure into the a0poster document? If I don't use subfigures, the file compiles, but then I'd have to rework all of my figures, which would be painful.

!Undefined control sequence
 <argument> if\@captype
              topcap
 I.154  \subfigure 
       [Figure A]{\label{fig:Sample-a}

(I'm using mactex, if that means anything)

Answer 1

I solved this problem by not using subfigure, but placing the figures explicitly and exactly. Kind of a dirty hack, but the poster went off well.

Answer 2

The following TeX file works just fine for me in PDFLaTeX. You need to describe your problem in more detail, perhaps by trying to prune it down to a minimal example.

\documentclass[a0]{a0poster}
\pagestyle{empty}
\setcounter{secnumdepth}{0}
\usepackage[absolute]{textpos}
\usepackage[it]{subfigure}
\usepackage{graphicx}
\begin{document}
\begin{figure}[htp]
  \begin{center}  
    \subfigure[Figure A]{\label{fig:Sample-a}\includegraphics[scale=5]{Image1.png}} 
    \subfigure[Figure B]{\label{fig:Sampple-b}\includegraphics[scale=5]{Image2.png}} 
  \end{center}
  \caption{This is my caption!}
\label{LineJustification}
\end{figure}
\end{document}

The version numbers of my pdfTeX, LaTeX, a0poster.cls, and subfigure.sty are as follows:

This is pdfTeXk, Version 3.1415926-1.40.9 (Web2C 7.5.7)
LaTeX2e <2005/12/01>
\ProvidesClass{a0poster}[2004/01/31 v1.22b a0poster class (GK, MW)]
\ProvidesPackage{subfigure}[2002/03/15 v2.1.5 subfigure package]

Answer 3

One wisdom I have heard: you should just do your posters as A4-sized articles with one page, and then print them as A0. Just use small enough font, like \footnotesize.