creating an eps file using tikz in Miktex 2.9

creating an eps file using tikz in Miktex 2.9

Hi I'm trying to use the tikz package to output an eps file, using miktex
2.9 in a windows 7 operating system. Before hand I appreciate you help!!!
The system message that I get is:
! Package tikz Error: Sorry, the system call 'latex -halt-on-error
-interaction =batchmode -jobname "fig_profits_dmr_melitz-figure0"
"\def\tikzexternalrealjob{
fig_profits_dmr_melitz}\input{fig_profits_dmr_melitz}" && dvips -o
"fig_profits _dmr_melitz-figure0".ps "fig_profits_dmr_melitz-figure0".dvi
&& ps2eps "fig_pro fits_dmr_melitz-figure0.ps"' did NOT result in a usable
output file 'fig_profit s_dmr_melitz-figure0' (expected one of
.epsi:.eps:.ps:). Please verify that you have enabled system calls. For
pdflatex, this is 'pdflatex -shell-escape'. Som etimes it is also named
'write 18' or something like that. Or maybe the command simply failed?
Error messages can be found in 'fig_profits_dmr_melitz-figure0. log'. If
you continue now, I'll try to typeset the picture.
See the tikz package documentation for explanation. Type H for immediate
help.
The code that I'm running is the following:
\documentclass{article} \usepackage{tikz}
% set up externalization \usetikzlibrary{external} \tikzexternalize[shell
escape=-enable-write18] % MikTeX uses a -enable-write18 instead of
--shell-escape.
\tikzset{external/system call={latex \tikzexternalcheckshellescape
-halt-on-error -interaction=batchmode -jobname "\image" "\texsource" &&
dvips -o "\image".ps "\image".dvi && ps2eps "\image.ps"}}
\begin{document} \begin{tikzpicture}[xscale=4,yscale=0.8] \draw <-> --
(0,6) node[above left]{$\Pi (\varphi)$} ; \draw [->] (0,0) -- (3,0)
node[below right]{$\varphi^{\sigma-1}$}; \node [above] at (.52999999,0)
{$\varphi$}; \draw [blue] (0,-.59049) -- (3,2.7519063); \node [below] at
(.62,0) {$\varphi^{M}$}; \draw [dashed,red] (0,-.59049) -- (3,2.2667197);
\node [above] at (1.1,0) {$\varphi^{x,M}$}; \draw [dashed,red]
((0,-3.1757969) -- (3,5.4854674); \node [below] at (1.17,0)
{$\varphi^{x}$}; \draw [blue] ((0,-3.1757969) -- (3,4.967272);
\end{tikzpicture} \end{document}