References are not appearing in the correct order [duplicate]

Question

I'm writing my thesis with the following format: My problem is that the references are not appearing in the correct, I'm having my first ref to be cited as 11 instead of 1! Although in the bibliography at the end it is shown in the correct order..

\documentclass[letter, onecolumn, 12pt] {report}
\usepackage{setspace}
\usepackage[numbers,sort&compress]{natbib}
\usepackage{algorithm2e}
\usepackage{multirow}
\usepackage{float}
\newtheorem{lemma}{Lemma}

\newtheorem{prob}{Problem}
\newtheorem{corollary}{Corollary}
\newtheorem{question}{Question}
\newtheorem{conjecture}{Conjecture}

\newenvironment{proof}{{\bf Proof.}}{\hfill\rule{2mm}{2mm}}

\newenvironment{remark}{\begin{remarka}\rm}{\end{remarka}}

\newtheorem{axiom}{Axiom}[section]
\newtheorem{defn}{Definition}[section]
\newtheorem{thm}{Theorem}[section]
\newtheorem{rem}{Remark}[section]
\newtheorem{prop}[thm]{Proposition}
\input{head.tex}
\begin{document}
\onehalfspacing
\maketitlepage

\pagenumbering{roman}

\setlength{\parskip}{.25cm}

EVERYTHING GOES HERE THE ABSTRACT AND CHAPTERS

\bibliographystyle{ieeetr}
\bibliography{JETCAS_2014_v2}
\end{document}