Lstlisting in beamer presentation

I have found the problem. The grey area displayed is for the caption of the code. Apparently it is grey because of the beamer style I am using.

So, setting captionpos to n in lstset fixes the problem.

Instead of using this trick, you can just add the option fragile in your frame

\begin{frame}[t,fragile]{\insertsectionhead}
\begin{columns}
    \begin{column}{0.6\textwidth}
    Calcul Symbolique (\textit{calcul formel})
        \begin{itemize}
            \item Algorithme sur les objets mathématiques
        \end{itemize}
        \Rcode
        \begin{lstlisting}
dsolve({diff(y(x),x,x)-3*y(x)=x,y(0)=1,D(y)(0)=2},y(x));
        \end{lstlisting}
    \end{column}
\end{frame}