Section references in RevTex 4.1

How does one reference sections in RevTex4.1? I've tried

• \section{\label{sec:Coupling}Coupling Efficiency}
• \section{Coupling Efficiency\label{sec:Coupling}}
• \section{Coupling Efficiency}\label{sec:Coupling}

But, in all cases \ref{sec:Coupling} has no error but simply prints a white space.

Here is a small doc that demonstrates the probelm (for one permutation):

\documentclass[12pt,preprint,longbibliography,aps,prl]{revtex4-1}
\usepackage{amsmath, amsthm, amssymb}
\usepackage{graphicx}
\usepackage{subfigure}
\usepackage{wrapfig}
\usepackage{color}

\begin{document}

\title{stuffing}
\author{John doe}

\begin{abstract}
stuff stuff stuff
\end{abstract}

\maketitle

\section{Introduction}
stuff stuff reference~\ref{sec:Coupling}

\section{\label{sec:Coupling}Coupling Efficiency}
stuff

\end{document}

• all of those should work, please make a complete (small) document that shows the problem. – David Carlisle Dec 16 '14 at 16:17
• The third option is the best, by the way. – Ruben Dec 16 '14 at 16:22
• If you \label{sec:Coupling} but \ref{sec:Expectation} you should get an error about undefined references. – Ruben Dec 16 '14 at 16:23

With the prl option of REVTeX section numbering is omitted, hence no reference is typeset, because plain \ref retrives only the section number. If you cancel this option you will have working references again.