Natbib "Author undefined" error

Question

After compiling, I receive several warnings of the following form:

Author undefined for citation`Lin1995' (natbib) on page 25

Here are some examples:

1. The relevant LaTeX code:

   For instance,~\citeauthor{Lin1995} observed...
   

   The corresponding text in the compiled document appears as:

   For instance, (author?) observed...
   

   The .bib entry:

   @article{Lin1995,
   annote = {less than half the corrision rate for any boundary fraction.},
   author = {Lin, P and Palumbo, G and Erb, U. and Aust, K.T.},
   doi = {10.1016/0956-716X(95)00420-Z},
   file = {:C$\backslash$:/Users/Oliver/Documents/Research/MIT/Papers/Influence of grain boundary character distribution on sensitization and intergranular corrosion of alloy 600 - Lin.pdf:pdf},
   issn = {0956716X},
   journal = {Scripta Metallurgica et Materialia},
   month = nov,
   number = {9},
   pages = {1387--1392},
   title = {{Influence of grain boundary character distribution on sensitization and intergranular corrosion of alloy 600}},
   url = {http://linkinghub.elsevier.com/retrieve/pii/0956716X9500420Z},
   volume = {33},
   year = {1995}
   }
   

2. But sometimes it gets the citation, just not the author, as in:

   ...the spectral framework of~\citet{Johnson2013}...
   

   which appears as:

   ...the spectral framework of (author?) [40]...
   

   and here is the .bib entry:

   @article{Johnson2013,
   author = {Johnson, Oliver K and Schuh, Christopher A},
   doi = {10.1016/j.actamat.2013.01.025},
   file = {:C$\backslash$:/Users/Oliver/Documents/Research/MIT/Papers/The uncorrelated triple junction distribution function - Johnson.pdf:pdf},
   issn = {13596454},
   journal = {Acta Materialia},
   keywords = {grain boundary engineering,microstructure design,triple junction,triple junction distribution function},
   month = may,
   number = {8},
   pages = {2863--2873},
   title = {{The uncorrelated triple junction distribution function: Towards grain boundary network design}},
   url = {http://linkinghub.elsevier.com/retrieve/pii/S1359645413000529},
   volume = {61},
   year = {2013}
   }
   

Here is my preamble, in case it is helpful:

\documentclass[12pt,twoside,singlespace]{mitthesis}
\usepackage{lgrind}
\usepackage{cmap}
\usepackage[T1]{fontenc}
\pagestyle{plain}

%---packages---%
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}

\usepackage{graphicx}
\usepackage{mathtools}
\usepackage{cases}
\usepackage[font=footnotesize]{caption}
\usepackage[section]{placeins}

\usepackage{leftidx}
\usepackage{mathrsfs}
\usepackage{bm}
\usepackage[numbers,sort&compress]{natbib}

%---macros---%
\newcommand{\threej}[6] {\begin{pmatrix} #1 & #2 & #3 \\ #4 & #5 & #6 \end{pmatrix}}
\newcommand{\sixj}[6] {\begin{Bmatrix} #1 & #2 & #3 \\ #4 & #5 & #6 \end{Bmatrix}}
\newcommand{\ninej}[9] {\begin{Bmatrix} #1 & #2 & #3 \\ #4 & #5 & #6 \\ #7 & #8 & #9 \end{Bmatrix}}
\newcommand{\so}[1]{\ensuremath{SO\left( #1 \right)}}
\renewcommand{\(}{\left(}
\renewcommand{\)}{\right)}
\renewcommand{\d}{\mathrm{d}}
\renewcommand{\figurename}{Fig.}

\DeclareMathOperator{\real}{Re\!}
\DeclareMathOperator{\imag}{Im\!}
\newcommand{\suchthat}{\;\ifnum\currentgrouptype=16 \middle\fi|\;}
\newcommand{\conj}{\,^{\scalebox{1}{$*$}}}
\newcommand{\CG}[6]{C_{#1,#2,#3,#4}^{#5,#6}}
\renewcommand{\(}{\left(}
\renewcommand{\)}{\right)}
\renewcommand{\d}{\mathrm{d}}

Answer 1

Fixed it... Just had to delete all of the temporary files and recompile (thanks to References not updating from BibTex)