Draw across two tikzpicture in subfigures

Question

I would like to draw a connection between two tikzpicture, each in a subfigure - in the following MWE, between the nodes n1 and n3. I think my code makes sense:

\documentclass[a4paper, 12pt]{article}

\usepackage{subcaption}
\usepackage{tikz}

\usetikzlibrary{automata, positioning, arrows, decorations.pathreplacing, calc, chains, shapes.misc}

\begin{document}

some text some more text

\begin{figure*}

%left subfigure
\begin{subfigure}[t]{.45\textwidth}
\begin{tikzpicture}[remember picture]
\node[draw, red] (n1) at (0,0) {};  
\end{tikzpicture}
\caption{Caption A}
\end{subfigure}
%
\hfill
% right subfigure
\begin{subfigure}[t]{.45\textwidth}
\begin{tikzpicture}[remember picture]
\node[draw, red] (n2) at (0,0) {};  
\node[draw, red] (n3) at (1,1) {};  
\end{tikzpicture}
\caption{Caption B}
\end{subfigure}

\begin{tikzpicture}[overlay]
\draw[blue] (n1) -- (n2);   
\end{tikzpicture}

\caption{Some caption for A and B.}
\end{figure*}


\end{document}

However, the results tells I am wrong (please note the blue line on the very top): :)

But I don't know what I am doing wrong.

Answer 1

Try like this:

\documentclass[a4paper, 12pt]{article}

\usepackage{subcaption}
\usepackage{tikz}

\usetikzlibrary{automata, positioning, arrows, decorations.pathreplacing, calc, chains, shapes.misc}

\begin{document}

some text some more text

\begin{figure*}

%left subfigure
\begin{subfigure}[t]{.45\textwidth}
\centering
\begin{tikzpicture}[remember picture]
\node[draw, red] (n1) at (0,0) {};  
\end{tikzpicture}
\caption{Caption A}
\end{subfigure}
%
\hfill
% right subfigure
\begin{subfigure}[t]{.45\textwidth}
\centering
\begin{tikzpicture}[remember picture]
\node[draw, red] (n2) at (0,0) {};  
\node[draw, red] (n3) at (1,1) {};  
\end{tikzpicture}
\caption{Caption B}
\end{subfigure}
\begin{tikzpicture}[overlay, remember picture]
\draw[blue] (n1) -- (n2);   
\end{tikzpicture}
\caption{Some caption for A and B.}
\end{figure*}

\end{document}