# Problems with PSTricks and Floating Point

When creating a picture with pstricks I want to do some simple calculations fot proper positioning. Therefore I use the "fp"-Package. It turns out that the usage of the \FPeval-command seems to shift the whole pspicture-coordinatesystem a bit to the right. Every time an \FPeval is executed. Has anyone suggestions to work around this phenomenon?

\documentclass{scrartcl}
\usepackage[nomessages]{fp}% http://ctan.org/pkg/fp
\usepackage{pstricks, pst-node, pst-plot}

\begin{document}

\begin{pspicture}[showgrid](-1, -1)(2, 1)

\cnode(1, 0){0pt}{itemID B}%

\FPeval\itemPosx{10}

\cnode(1, 0){0pt}{itemID B}%

\end{pspicture}

\end{document}