General ⇒ pgf missed package

[Spider]

Hi all,
I am working on a presentation using beamer and I would like to display a series of images with a specified delay. I found the following code:

Code: Select all

\frame{
\only<1>{
\begin{centering}
  \pgfimage[scale=.5]{fish1.jpg}
  \par
\end{centering}}

\transduration<2>{5}

\only<2>{
\begin{centering}
  \pgfimage[scale=.5cm]{fish2.jpg}
  \par
\end{centering}}

\transduration<3>{5}

\only<3>{
\begin{centering}
 \pgfimage[scale=.5cm]{fish3.jpg}
 \par
\end{centering}}
}

I got a message error that I missed a required package.
Can anyone tell me the suitable package for that?
Thank you!