Consider:
\documentclass[12pt]{article}
\usepackage{tkz-euclide,tkz-fct}
\usetkzobj{all}
\begin{document}
\begin{tikzpicture}
\tkzInit[xmin=-3,xmax=3,xstep=1,ymin=0,ymax=.4,ystep=0.2]
\tkzDrawX[right=3pt,label={$Z$}]
\tkzLabelX[step=1]
\tkzFct[thick,color=blue,domain=-3:3]{1/sqrt(2pi)exp(-0.5\x2)}
\tkzDrawArea[color=red!50,domain=-1.439531:1.439531]
\tkzTextcolor=black{85%}
\tkzDefPoints{1.439531/-0.2/A,1.439531/0/B, -1.439531/-0.2/C,-1.439531/0/D}
\tkzDrawVectors[red](A,B C,D)
\tkzTextbelow=3pt,color=red{$z^{}$}
\tkzTextbelow=3pt,color=red{$-z^{*}$}
\end{tikzpicture}
\end{document}
For some reason, this produces the following image where the area slants up on the left.

Can anyone see a problem with my code or is this a bug?
D.