tikz matrix and beamer

Question

Possible Duplicate:
Unknown error using tikz matrix of nodes in beamer

I would put the following figure in a beamer slide

I tried with [ampersand replacement=\&] but it does not work

\documentclass[11pt]{article} 
%\documentclass{beamer}

\pagestyle{empty}  
\usepackage{tikz}
\usetikzlibrary{positioning,calc,matrix}

\begin{document}
\centering

%\begin{frame}
\begin{figure}[H]\centering
\begin{tikzpicture}

 \matrix[matrix of math nodes] (m1)
  {|[font=\scriptsize,red]| rang    &|[font=\scriptsize,red]| 5 &|[font=\scriptsize,red]| 4 &|[font=\scriptsize,red]| 3 &|[font=\scriptsize,red]| 2 &|[font=\scriptsize,red]| 1 &|[font=\scriptsize,red]| 0 &       &   &           &       &\\
        & Bu    & Ga& Zo    &Meu& Ga& Bu    &       &   &           &           &       &\\
            &       &       &       &       &       &       & 4^0   & \to   &Bu\cdot 4^0    &=1\cdot 4^0    &=      &1 \\
            &       &       &       &       &       &       & 4^1   & \to   &Ga\cdot 4^1    &=0\cdot 4^1    &=      &0\\
            &       &       &       &       &       &       & 4^2   & \to   &Meu\cdot 4^2   &=3\cdot 4^2    &=      &48\\
            &   &       &       &       &       &       & 4^3   & \to   &Zo\cdot 4^3    &=2\cdot 4^3    &=      &128\\
            &   &       &       &       &       &       & 4^4   & \to   &Ga\cdot 4^4    &=0\cdot 4^4    &=      &0\\
            &   &       &       &       &       &       & 4^5   & \to   &Bu\cdot 4^5    &=1\cdot 4^5    &=      &1024\\   
            &   &       &       &       &       &       &       &   &           &           &+      &1201\\                
    };

\draw[-latex] (m1-2-7) |- (m1-3-8);
\draw[-latex] (m1-2-6) |- (m1-4-8);
\draw[-latex] (m1-2-5) |- (m1-5-8);
\draw[-latex] (m1-2-4) |- (m1-6-8);
\draw[-latex] (m1-2-3) |- (m1-7-8);
\draw[-latex] (m1-2-2) |- (m1-8-8);

\end{tikzpicture}

\caption{Transcodade base 4 (Shadok) $\to$ base 10}
\label{fig:base4tobase10}
\end{figure}
%\end{frame}

\end{document}