Problem in creating bibliography for each chapter

Question

I am having problem in enclosing bibliography after each chapter. In fact the bibliography of first chapter is repeating after each chapter with ? mark in the main text of the second chapter onwards. Here is what I am doing: The main TeX file:

\usepackage[square, comma, sort&compress]{natbib}
\begin{document}
...
...
\begin{thesis}

\headingsoff
\headingson
\include{ch1/ch1}
\include{ch2/ch2}
......
....
\end{thesis}
\end{document}

Each chapter is as follows:
\chapter{chapter 1}
{\large
\section{Introduction}
\label{intro}
.....
.....
\bibliographystyle{bibstyle/thesis_bib}
\bibliography{ch1/bib/myref}
}

I am compiling main.tex as LaTeX and then BibTeX and back as LaTeX. The ref in 1st chapter is coming alright. But second chapter onwards it is giving problem. I have separate bib file for each chapter. Please help me finding out where I have done mistake.

Thanks