Unable to convert references from IEEEtran style to apacite

I have written a paper with bibliography in IEEEtran style. Everything was compiled and generated properly.
Now I have been asked to convert the references to APA style.
I have added pacakge and bibstyle apacite.sty. Now I am unable to compile it. Undefined references messages are popping-up.
My latex file looks like this:

    documentclass[conference]{IEEEtran}

    ifCLASSINFOpdf
       usepackage[pdftex]{graphicx}
 DeclareGraphicsExtensions{.pdf,.jpeg,.png}
 else
 usepackage[dvips]{graphicx}
DeclareGraphicsExtensions{.eps}
fi

usepackage{fixltx2e}

ifCLASSOPTIONcompsoc
  usepackage{subfig}
else
  usepackage{subfig}
fi

usepackage{txfonts}
usepackage{multirow}
%usepackage{apacite}


providecommand{e}[1]{ensuremath{times 10^{#1}}}

begin{document}
 blah blah blah

 bibliographystyle{IEEEtran/bibtex/IEEEtran}
 %bibliographystyle{apacite}
bibliography{bibfile}

 end{document}

Latex messages are:

This is pdfTeX, Version 3.1415926-1.40.10 (TeX Live 2009/Debian)
entering extended mode
(./ije.tex
LaTeX2e <2009/09/24>
Babel <v3.8l> and hyphenation patterns for english, usenglishmax,         dumylang, nohyphenation, loaded.
(./IEEEtran.cls
Document Class: IEEEtran 2014/09/17 V1.8a by Michael Shell
-- See the "IEEEtran_HOWTO" manual for usage information.
 -- http://www.michaelshell.org/tex/ieeetran/
 (/usr/share/texmf-texlive/tex/latex/psnfss/ot1ptm.fd)
  -- Using 8.5in x 11in (letter) paper.
 -- Using DVI output.
 -- This is a 10 point document.
 ) (/usr/share/texmf-texlive/tex/latex/graphics/graphicx.sty
 (/usr/share/texmf-texlive/tex/latex/graphics/keyval.sty)
 (/usr/share/texmf-texlive/tex/latex/graphics/graphics.sty
 (/usr/share/texmf-texlive/tex/latex/graphics/trig.sty)
  (/etc/texmf/tex/latex/config/graphics.cfg)
  (/usr/share/texmf-texlive/tex/latex/graphics/dvips.def)))
  (/usr/share/texmf-texlive/tex/latex/base/fixltx2e.sty)
  (/usr/share/texmf-texlive/tex/latex/subfig/subfig.sty (./caption3.sty)) 
 (/usr/share/texmf-texlive/tex/latex/txfonts/txfonts.sty)
 (/usr/share/texmf-texlive/tex/latex/multirow/multirow.sty)        (./apacite.sty)
 (./ije.aux) (/usr/share/texmf-texlive/tex/latex/txfonts/omltxmi.fd)
 (/usr/share/texmf-texlive/tex/latex/txfonts/omstxsy.fd)
 (/usr/share/texmf-texlive/tex/latex/txfonts/omxtxex.fd)
 (/usr/share/texmf-texlive/tex/latex/txfonts/utxexa.fd)
 (/usr/share/texmf-texlive/tex/latex/txfonts/ot1txr.fd)
 -- Lines per column: 56 (exact).


 (/usr/share/texmf-texlive/tex/latex/txfonts/utxmia.fd)
 (/usr/share/texmf-texlive/tex/latex/txfonts/utxsya.fd)
 (/usr/share/texmf-texlive/tex/latex/txfonts/utxsyb.fd)
  (/usr/share/texmf-texlive/tex/latex/txfonts/utxsyc.fd)


 LaTeX Warning: Reference `leakage' on page 1 undefined on input line 69.

 <gatelength.eps> <dynamic.eps> <leakage.eps>

  LaTeX Warning: Citation `chandrakasan1992low' undefined on input line      93.

 [1]

      LaTeX Warning: Citation `lee2004gate' undefined on input line 102.


    LaTeX Warning: Reference `igate' on page 2 undefined on input line 102.

    <igate.eps>
 ! Illegal parameter number in definition of reserved@a.
  <to be read again> 
               }
 l.108 ...an nmos transistor cite{choi2001impact}}
  ?

I have put all the apacite files in the common folder.
Please help.