Can't set bibliography in a llncs tex document

Question

My .tex file is as follows:

\documentclass{llncs}

\begin{document}

%TITLE
\title{TITLE}
\author{AUTHORS}
\institute{INSTITUTE}
\maketitle

%ABSTRACT
\begin{abstract}
Abstract here
\end{abstract}

%SECTION 1
\section{Introduction}

%SECTION 2
\section{Related Work}

Citation test \cite{Otto2012}

%
% ---- Bibliography ----
%
%\begin{thebibliography}{}
\bibliographystyle{splncs}
\bibliography{test}
%\end{thebibliography}
\end{document}

Also my .bib file is the following:

@article{Otto2012,
  author =   {M.~Otto},
  title =    {Highly acyclic groups, hypergraph covers and the guarded fragment},
  journal =      {Journal of the ACM},
  year =     {2012},
  volume =       {59}
}

Unfortunately I don't see the citation or the reference in my pdf document after I compile the tex file. What I am doing wrong? Note that my .bib file is under the same directory as my .tex file.