Problem creating 3d intersection of surfaces

Question

I'm trying make an intersection of two surfaces but appears a warning message:

Package pgfplots Warning: You have an axis with empty range (in direction y). R eplacing it with a default range and clearing all plots. on input line 52.

Why this ocurrs?

\documentclass{standalone}

\usepackage{tikz,pgfplots}
\usepgfplotslibrary{colormaps}
 \pgfplotsset{compat=1.11}


\begin{document}
 \begin{tikzpicture}
   \begin{axis}[
       domain = -4:4,
       zmax   = 50,
       colormap/bone,
       grid
               ]
     \addplot3 [surf,color=white] {-x^2-y^2};
  \end{axis}
 \end{tikzpicture}

 \begin{tikzpicture}
  \begin{axis}[axis on top,axis lines=center,xtick=\empty,ytick=\empty,ztick=\empty,view={130}{30},xmax=1.2,ymax=1.2,zmin=0,zmax=0.03]
 %\addplot3[surf,samples=25,domain=0:1,shader=interp] {x*(1-x)*y*(1-y)};
     \addplot3[surf,color=white,domain=-1:1] {-x^2-y^2};
     \addplot3[surf,samples=25,domain=0:1] {x-y-1.1};
  %\addplot3 [surf,fill=white] coordinates { (1.1,0,0) (0,1.1,0) (0,1.1,0.02) (1.1,0,0.02) };
  \end{axis}
 \end{tikzpicture}
\end{document}

Compare images because the equation -x^2-y^2.

Answer 1

You got the message "Package pgfplots Warning: You have an axis with empty range (in direction y)" because you set xmax and ymax values but not xmin and ymin. Once you add xmin=0, ymin=0, for example, that message goes away.