I am making a 3x3 matrix of plots in a beamer slide. Position (1,1) is empty, the rest of the first row has column titles and the rest of the first column has row titles. Positions (2,2) to (3,3) contain actual plots. I am using groupplots (pgfplots 1.12) to make such a matrix.
I receive the following two error messages:
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 139.
! Package pgfplots Error: Error: Plot width `28.45274pt' is too small. This can not be implemented while maintaining constant size for labels. Sorry, label siz es are only approximate. You will need to adjust your width..
In the case of the second error, I don't really know where to increase the width. Can you please help me to fix my code so I don't get the errors mentioned above?
The intended outcome is the following image.

My code so far is as follows:
\documentclass{beamer}
\usepackage{pgfplots}
\usetikzlibrary{pgfplots.groupplots}
\pgfplotsset{compat=1.12}
\pgfmathdeclarefunction{gauss}{2}{%
\pgfmathparse{1/(#2*sqrt(2*pi))*exp(-((x-#1)^2)/(2*#2^2))}%
}
\begin{document}
\begin{frame}{Distribution Matrix}
\begin{tikzpicture}
\begin{groupplot}[
group style={
group name=my plots,
group size=3 by 3,
},
footnotesize,
tickpos=left,
ytick align=outside,
xtick align=outside,
enlarge x limits=false
]
\nextgroupplot[
width=1cm,
height=1cm,
hide axis]
\nextgroupplot[
width=5cm,
height=1cm,
no markers, domain=0:9, samples=100,
axis line style = { draw = none },
xlabel style={at={(axis description cs:0.5,-0.01)},anchor=north},
xlabel={Column 1},
ticks=none,
axis on top]
\nextgroupplot[
width=5cm,
height=1cm,
no markers, domain=0:9, samples=100,
axis line style = { draw = none },
xlabel style={at={(axis description cs:0.5,-0.01)},anchor=north},
xlabel={Column 2},
ticks=none,
axis on top]
\nextgroupplot[
width=1cm,
height=4cm,
no markers, domain=0:9, samples=100,
axis lines=center,
axis line style = { draw = none },
ylabel style={at={(axis description cs:-0.01,0.5)},rotate=90,anchor=south},
ylabel={Row 1},
ticks=none,
axis on top]
\nextgroupplot[
width=5cm,
height=4cm,
no markers, domain=0:9, samples=100,
axis lines=center,
axis line style={->},
xlabel style={at={(axis description cs:0.5,-0.01)},anchor=north},
ylabel style={at={(axis description cs:-0.01,0.5)},rotate=90,anchor=south},
ticks=none,
axis on top]
\addplot [very thick,cyan!50!black] {gauss(4,1)};
\addplot [thick,red, no markers] coordinates {(5.5,0.0) (5.5,0.4)};
\nextgroupplot[
width=5cm,
height=4cm,
no markers, domain=0:9, samples=100,
axis lines=center,
axis line style={->},
xlabel style={at={(axis description cs:0.5,-0.01)},anchor=north},
ylabel style={at={(axis description cs:-0.01,0.5)},rotate=90,anchor=south},
ticks=none,
axis on top]
\addplot [very thick,cyan!50!black] {gauss(4,1)};
\addplot [thick,red, no markers] coordinates {(5.5,0.0) (5.5,0.4)};
\nextgroupplot[
width=1cm,
height=4cm,
no markers, domain=0:9, samples=100,
axis lines=center,
axis line style = { draw = none },
ylabel style={at={(axis description cs:-0.01,0.5)},rotate=90,anchor=south},
ylabel={Row 2},
ticks=none,
axis on top]
\nextgroupplot[
width=5cm,
height=4cm,
no markers, domain=0:9, samples=100,
axis lines=center,
axis line style={->},
xlabel style={at={(axis description cs:0.5,-0.01)},anchor=north},
ylabel style={at={(axis description cs:-0.01,0.5)},rotate=90,anchor=south},
ticks=none,
axis on top]
\addplot [very thick,cyan!50!black] {gauss(4,1)};
\addplot [thick,red, no markers] coordinates {(2.5,0) (2.5,0.4)};
\addplot [thick,red, no markers] coordinates {(5.5,0.0) (5.5,0.4)};
\nextgroupplot[
width=5cm,
height=4cm,
no markers, domain=0:9, samples=100,
axis lines=center,
axis line style={->},
xlabel style={at={(axis description cs:0.5,-0.01)},anchor=north},
ylabel style={at={(axis description cs:-0.01,0.5)},rotate=90,anchor=south},
ticks=none,
axis on top]
\addplot [dashed,very thick,cyan!50!black] {gauss(4,1)};
\addplot [very thick,cyan!50!black] {gauss(5,1)};
\addplot [thick,red, no markers] coordinates {(2.5,0) (2.5,0.4)};
\addplot [thick,red, no markers] coordinates {(5.5,0.0) (5.5,0.4)};
\end{groupplot}
\end{tikzpicture}
\end{frame}
\end{document}
Thanks in advance!
