[pstricks] Scale and clip. Lines from psline suddenly vanishes.

[Christer Gustafsson]

A very long and thin object is drawn in a sequence of pspictures by 
means of pspicture, rput and psclip.
The pictures feature text and pslines.

For certain parts of the object, a high degree of magnification is 
desired in order to see some details.
These "zoom" pictures fails to show.

The example below illustrates my problem. Within the psclip environment 
one text string
and two lines are included. With a length unit set to 4.2cm  both text 
and lines are drawn.
With a length unit equal to 4.3 cm only the text is drawn --- both lines 
are mysteriously gone.

Has anybody an explanation of what error I commit?

Christer




\documentclass[10pt,a4paper]{article}
\usepackage{pst-plot}
\begin{document}
\begin{figure}
\begin{pspicture}(  0.00,  0.00)(  16.00,  20.00)
\psset{xunit=4.2cm,yunit=4.2cm}   % Lines shown
%\psset{xunit=4.3cm,yunit=4.3cm}  % No lines shown
\rput[bl](1,-27.00){%
\begin{psclip}{\psframe[linecolor=white](-1.00,27.00)(1.00,30.00)}
   \psline(-1,27)(1,30)
   \psline(-0.5,27.5)(0.5,27.5)
   \rput[0,0]{0}(0.0,28.5){Text}
\end{psclip}
}% End rput
\end{pspicture}
\caption[Short]{Long}
\end{figure}
\end{document}