[Tex/LaTex] Undefined control sequence error in \cite when compiling

Question

This is the start of the .tex file :

\documentclass{llncs}  
\newcommand{\modelName}{ABC}  %This is the name of the model  
\title{XYZ}  
\begin{document}

\section{Introduction}  

Believable non-playable characters are critical to creating an immersive character-rich game world whether it is for entertainment or training \cite{reilly1996believable}.

\bibliographystyle{splncs}
\bibliography{aiide2014mx}

I am getting the following error with the above line. If anyone has any idea about this it would be really helpful! I do have the entry for the citation in the bib file. So I am not sure why I am getting this error.

! Undefined control sequence.
\b@reilly1996believable ->\citeauthoryear
{Reilly}{1996}
l.90 ...nt or training \cite{reilly1996believable}
. Emotionally plausible ch...
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.

The .bib file is:

@techreport{reilly1996believable,
Author = {Reilly, W Scott},
Date-Added = {2014-05-13 05:53:57 +0000},
Date-Modified = {2014-05-13 05:53:57 +0000},
Institution = {Defense Technical Information Center (DTIC) Document},
Title = {{Believable Social and Emotional Agents.}},
Year = {1996}}

Answer 1

Maybe your kernel file is not updated. This is how the following output results. Go to Springer and download the zip file llncs2e.zip then extract llncs.cls into your working directory.

Code

\documentclass{llncs}  
\newcommand{\modelName}{ABC}  %This is the name of the model  
\title{XYZ}  
\begin{document}

\section{Introduction}  

Believable non-playable characters are critical to creating an immersive character-rich game world whether it is for entertainment or training \cite{reilly1996believable}.

\bibliographystyle{splncs}
\bibliography{aiide2014mx}
\end{document}