I'm writing a paper in LaTeX at the moment. I'm using the \usepackage{apacite}, but for some reason, the years will not show up in my in-text citations. The entry in the References section is fine, however. The entry in the BibTeX file is perfect; I'm reasonably positive that that isn't the problem.
My citation should look like this: (Binney & Tremaine, 2011). However, it just comes up as (Binney & Tremaine, ) and gives me a whole bunch of error messages. Here is my code. I would appreciate any answers.
\documentclass[12pt]{article}
\usepackage{amsmath,amsfonts}
\usepackage{amsthm,upref}
\usepackage{apacite}
\usepackage{enumerate}
\usepackage{graphicx}
\usepackage{caption}
\usepackage[usenames,dvipsnames,svgnames,table]{xcolor}
\usepackage{geometry}\geometry{margin=2cm}
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{tkz-euclide}
\usepackage{hyperref}
%\usepackage{fullpage}
\usepackage{float}
\usepackage{url}
%\usepackage{multicol}
\usepackage{physics}
\providecommand{\e}[1]{\ensuremath{\times 10^{#1}}}
\title{}
\author{}
\date{10/8/2015}
\begin{document}
\maketitle
\section{Measures of distance}
\subsection{Part (a)}
... the parsec is now defined as exactly $648,000/\pi$ AU \cite{bintrem}...
\bibliography{biblio}{}
\bibliographystyle{apacite}
\end{document}