beamer error

[Patrick Dupre]

This error is now fixed, but to get A4 output size, I set
\usepackage{pgfpages}
\pgfpagesuselayout{4 on 1}[a4paper]

but I get the error:
\pdfpages at includegraphics@status=\count340
\AM at pagebox=\box78
\AM at global@opts=\toks49
\AM at pagecnt=\count341
\AM at toc@title=\toks50
\AM at lof@heading=\toks51
\c at AM@survey=\count342
\AM at templatesizebox=\box79
)
! Undefined control sequence.
<recently read> \pdfpagesuselayout

l.46 \pdfpagesuselayout
                       {4 on 1}[a4paper]
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.


! LaTeX Error: Missing \begin{document}.