Lstlisting duplicate caption

Question

I've been trying to insert the code to my LaTeX document. I used this piece of code:

\begin{lstlisting}[label={lst:rws}, captionpos={bottom}, caption={Pseudo-code of RWS Selection}]
r = Random(); /* Uniformly distributed random number in [0,1] */
sum = 0;
for (i = 1; i < population.size; i++)
    sum += individual(i).probabilityOfSelection;
    if (sum >= r)
        select(i)
\end{lstlisting}

However I get duplicated caption at the top of the listing and also at the bottom. If I don't use captionpos={bottom} I get caption on top of the listing. Any idea what might be causing it? Here's what I get:

Thanks

Answer 1

If you just provide captionpos={b} - as it is stated in the manual - it is working fine.

\documentclass[border=2mm]{standalone}
\usepackage{listings}
\begin{document}
\begin{lstlisting}[
    label={lst:rws},
    captionpos={b},
    caption={Pseudo-code of RWS Selection}
]
r = Random(); /* Uniformly distributed random number in [0,1] */
sum = 0;
for (i = 1; i < population.size; i++)
    sum += individual(i).probabilityOfSelection;
    if (sum >= r)
        select(i)
\end{lstlisting}
\end{document}

(Nonetheless it is the question, if the "non-valid" value shouldn't raise an error ...)