[Pgfplots-features] gnuplot error (gp 5.0 rc1) in pgfplots generated gp code

[Matthias P. <mat...@gm...>]

Hello,
I tried to report a bug using sourceforge, but although I logged into 
sf, I got no
button or link to report a bug?

This is my problem:
In my template I use an example of pgfplots which uses gnuplot.
Lately I installed the latest gunplot windows version which is 5.0rc1
Now the code of pgfplot fails.

This is the code

\pgfplotsset{width=0.8\textwidth, height=0.6\textwidth}
\pgfplotsset{samples=2000}
\centering
\begin{tikzpicture}
\begin{axis}[
   xlabel=$x$,
   ylabel={$\sin(x) (x+1) + 3x$},
   grid=major,
   /pgfplots/enlargelimits=false,
   ymax=500,
   /pgfplots/xtick={0,20,...,100},
   /pgfplots/ytick={0,100,...,600},
]
%
\addplot[domain=0:100, blue,style={line width=0.7pt}]
   gnuplot{sin(x)*(x+1) + 3*x};
%
\legend{$\sin(x) (x+1) + 3x$}
\end{axis}
\end{tikzpicture}

And this the error message of gnuplot:
set format "%.7e";; set samples 2000; set dummy x,y; plot [x=0:100] 
sin(x)*(x+1) + 3*x; ^ "TemplateDocumentation.pgf-plot.gnuplot", line 2: too


many dummy variables


My gnuplot knowledge and especially the changes from 4 to 5 are too 
little to know what causes this error.

Matthias