[Xy-pic] Squeezed Circles

[John G. Michopoulos]

Dear all,

I am a newbie on XY-pic and cannot figure out what causes the circle nodes
of the graph given by the example code below to appear squeexed horizontally
appearing in fact as elipses!

My environment is MikTeX (LaTeX2e) under W2K and xy-pic is v.3.7

This happens ONLY when I use the \xymatrix.

When I use \xygraph I get perfect round circles!

I would immensely apreciate any help on this!

Here's the code:
--------------------snip----------------------

\documentclass[jsco]{academic}
\usepackage{amssymb,amsfonts,amsbsy}
%
\input xy
\xyoption{ps} \xyoption{dvips} \xyoption{all}
%\xyReloadDrivers
%
% \usepackage[ps,dvips,all]{xy} %[ps,dvips,all]
% \SelectTips{cm}{}   %
%
\begin{document}


\shortauthor{ }

\shorttitle{ }

%
% \SelectTips{cm}{}
%
\def\Mnode#1{*++[o][F-:thicker]{#1}}
\def\Mnodez#1{*++[o][F=:thicker]{#1}}
\def\Lmnode#1#2#3#4{\Mnode{#1}="#1"
\POS="O"-(#3,#4)*!R\txt{\small #2} \POS"O" +(-#3,-#4) \POS"O"}
\def\Lmnodez#1#2#3#4{\Mnodez{#1}="#1"
\POS="O"-(#3,#4)*!R\txt{\small #2} \POS"O" +(-#3,-#4) \POS"O"}
%
\newdir{|>}{!/5.5pt/\dir{|}
*:(1,-.2)\dir^{>} *:(1,+.2)\dir_{>}} % define open trig arrow head
%
% \xyoption{color}
% \xyoption{line}
Why are the circles squeezed?
$$
\xymatrix {  \Mnode{00} {\ar @*{[thicker]}[rr]^-{NEW2}} & &
*++[o][F-:thicker:red]{01}
\ar[rr]^{\varphi\bot,a} {\ar @{|>}[dr]^{label2}} & \hole &\Mnodez{02} \\
& \Lmnode {06}{$T_{uv}$}{-7.0}{-6.0}&& \Mnode{04} \ar
@^{>}[r]^{over}& \Lmnodez {05}{$S_{uv}$}{-7.0}{-6.0} \ar
@^{>}[l]^{under} }
$$
%
\end{document}
=======================snip========================

Thank you greatly!

-john m

=========================================
Dr. John G. Michopoulos
Naval Research Laboratory, Code 6303
Computational Mutliphysics Systems Lab
Washington DC 20375, USA       
tel.202.767.2189  fax.202.767.9181
e-mail: john.michopoulos@nrl.navy.mil