[XeTeX] Xetex & beamer transition effects problem

[snvv]

Hello
I try to use some slide transitions but it does not work.
Is it possible to have transitions with xetex & beamer?

Thank you
snvv

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For example see the following code bellow:

\documentclass{beamer}
\usepackage{fontspec,fontenc,xunicode,xltxtra,xgreek} %xgreek
\usepackage{textfit} %For scale
\usepackage[varg]{txfonts}

\setbeamertemplate{navigation symbols}{}
\usetheme{Antibes} %

\AtBeginSection[]
{
  \begin{frame}<beamer>
    \frametitle{Gliederung}
    \tableofcontents[currentsection,currentsubsection]
  \end{frame}
}


\begin{document}

\title {}
\institute[]{}
\author {}
\date []{}

\begin{frame}
\frametitle{Example of Transboxin}
\transboxin
Frame Body Text 
\end{frame}


\begin{frame}
\frametitle{Example of Transboxin}
\transboxin
Frame Body Text No2
\end{frame}
\end{document}