[pstricks] Inquiry: how to use pstricks properly

[Baronin Putzele Storch von Duenen und Langenhals]

I am rather new to pstricks. I have been collecting all the possible
informations and documentations and reading it.. still
most stragely, I cannot get some things to work... in particular, in trees,
the labels on edges do not appear correctly.

I used the following example, which  is in the part on trees

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -*- Mode: Latex -*-
%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Trees-Game.tex --- Game tree example: a standard signalling game
%%
%% Author          : Dave SCHMIDT (Indiana University - USA)
%%                                <drschmid at indiana.edu>
%% Created the     : 1996
%% Last mod. by    : Denis GIROU (CNRS/IDRIS - France)
<Denis.Girou at idris.fr>
%% Last mod. the   : Wed Apr  2 22:00:52 1997
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%

\documentclass{article}

\usepackage{pst-tree}

\pagestyle{empty}

\begin{document}

\psset{radius=6pt,dotsize=4pt,treefit=loose}

\begin{center}
  {\Large Signalling Game}
  \vspace{.3in}

  \pstree[treemode=R]
    {\Tcircle{0}}
    {\pstree{\Tcircle{1}^{X}_{$\frac{1}{2}$}}
            {\pstree{\Tcircle[name=XU2,linestyle=dashed]{2}^{U}}
                    {\Tdot~{(0,0)}^{L}
                     \Tdot~{(4,1)}_{R}}
             \pstree{\Tcircle[name=XD2,linestyle=dashed]{2}_{D}}
                    {\Tdot~{(3,0)}^{L}
                     \Tdot~{(1,1)}_{R}}}
     \pstree{\Tcircle{1}^{$\frac{1}{2}$}_{Y}}
            {\pstree{\Tcircle[name=YU2,linestyle=dashed]{2}^{U}}
                    {\Tdot~{(1,2)}^{L}
                     \Tdot~{(2,0)}_{R}}
             \pstree{\Tcircle[name=YD2,linestyle=dashed]{2}_{D}}
                    {\Tdot~{(3,3)}^{L}
                     \Tdot~{(0,1)}_{R}}}}
  % Other connections
  \ncarc[linestyle=dashed,arcangle=-20]{XU2}{YU2}
  \ncarc[linestyle=dashed,arcangle=20]{XD2}{YD2}
\end{center}

\end{document}

the tree builts okay, but the labels mess up with the nodes.. why?


Could somebody explain what I should do.
I use the Miktex 2.1 version the largest of both available..
thank you in advance.