[OS X TeX] Memoir figure problem

[David Arnold]

All,

I am trying an example from memman.pdf using the memoir class.

\documentclass{memoir}

\begin{document}

\begin{figure}
\centering
\begin{minipage}{0.45\textwidth}
Hello
\subcaption{Bar chart.}
\end{minipage}\hfill
\begin{minipage}{0.45\textwidth}
Hello
\subcaption{Bar chart.}
\end{minipage}
\caption{my caption\label{fig:BarAndLinePlot}
\end{figure}

\end{verbatim}

\end{document}

I am getting this error:

! LaTeX Error: No counter 'subfigure' defined.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
  ...

l.9 \subcaption
                {Bar chart.}

Any suggestions?

David.