title: Latex/Miktex: Undefined citations
body: <p>I am writing a latex script for my work, and I am having infinite trouble in getting the references in the PDF. My code is shown below, and I am using MikTex 2.9 on RStudio. Some background information that might be relevant:</p>
  
  <ul>
  <li>I am using Mendeley for my references, which I have set up correctly (as it seems) to Enable bibtex syncing</li>
  <li>The .bib file doesn't seem to look strange to me (Irungu is added below)</li>
  <li>I am using the exact same script as my colleagues (apart from the different path referring to my articles), and they are having no issues compiling it into pdf.</li>
  <li>The errors regarding citations are:
  Citation Draganovic2013 on page 1 undefined on input line xx
  Citation Irungu2019 on page 1 undefined on input line xx
  There were undefined citations</li>
  </ul>
  
  <p>I hope one of you is able to help me out! 
  Cheers!</p>
  
  <pre><code>@article{Irungu2019,
  abstract = {A composite blend consisting of sunflower cake, maize germ, wheat bran, fresh water shrimps and cassava flour was extruded using a single-screw extruder to produce expanded fish feed pellets. The effects of temperature (80–120 °C), die diameter (2–4 mm), and feed pre-conditioning time (50–150 s; steam 400 kPa) on properties of the pellets (expansion ratio, bulk density, floatability, durability, water absorption, water solubility, water stability, and in-vitro protein digestibility) were investigated using response surface methodology. Regression equations describing the effect of each variable on the product responses were obtained. The pellets extruded using a factor combination of 120 °C extruder barrel temperature, 2 mm die diameter, and 100 s of feed pre-conditioning time gave most desirable pellet floatability (100{\%}), durability index (99{\%}), expansion ratio (2.64), water absorption index (4.12), water solubility index (9.31), water stability (87{\%}), bulk density (479 g/L), and in vitro protein digestibility (69.97{\%}) with a composite desirability of 0.88. Practical applications: Extrusion is a modern feed processing method whose use is fast gaining popularity among small feed processors in developing countries. However, extrusion is a process that involves many parameters that need to be optimized for desirable end properties. These findings guide fish feed manufacturers on the optimum conditions for single screw extruders for production of feeds with desirable properties especially for the fish types that are top feeders. In addition, the results offer important insights on how temperature, die diameter, and feed pre-conditioning, may be manipulated to influence properties of extruded aquafeed when using simple low-cost small-scale extruders.},
  author = {Irungu, Francis Gichuho and Mutungi, Christopher and Faraj, Abdul and Affognon, Hippolyte and Ekesi, Sunday and Nakimbugwe, Dorothy and Fiaboe, Komi K.M.},
  doi = {10.1111/jfpe.12980},
  file = {:L$\backslash$:/Marjanne/ScientificArticles/Irungu2019.pdf:pdf},
  issn = {17454530},
  journal = {Journal of Food Process Engineering},
  number = {2},
  pages = {1--12},
  title = {{Optimization of extruder cooking conditions for the manufacture of fish feeds using response surface methodology}},
  volume = {42},
  year = {2019}
  }
  </code></pre>
  
  <pre><code>\documentclass[10pt,a4paper]{article}
  \usepackage{etoolbox}
  \usepackage{mathpazo}
  \renewcommand{\sfdefault}{lmss}
  \renewcommand{\ttdefault}{lmtt}
  \usepackage{geometry}
  \usepackage[usenames,dvipsnames]{xcolor}
  % \geometry{verbose,tmargin=2cm,bmargin=2cm,lmargin=2.5cm,rmargin=2.5cm}
  \geometry{verbose,tmargin=2cm,bmargin=2cm,lmargin=2.5cm,rmargin=2.5cm}
  \usepackage[margin=10pt,font=small,labelfont=bf,labelsep=colon]{caption}
  \usepackage{amstext}
  %% \usepackage{esint}
  \usepackage[english]{babel}
  \usepackage{eurosym}
  \usepackage{booktabs}
  \usepackage[parfill]{parskip}
  \usepackage[round]{natbib}
  %\usepackage{caption}
  \usepackage{pdfpages}
  \usepackage[figuresright]{rotating}
  \usepackage{longtable}
  \usepackage[version=4]{mhchem}
  \usepackage{todonotes}
  \usepackage{hyperref}
  \usepackage{subfig}
  \usepackage{array}
  \usepackage{float}
  \usepackage{lipsum}
  \usepackage{lastpage}
  \usetikzlibrary{patterns}
  \usetikzlibrary{shapes.geometric}
  \usepackage{textcomp}
  
  
  \begin{document}
  
  
  \title[Title of Document]
  
  \begin{document}
  
  \begin{titlepage}
  \maketitle
  \end{titlepage}
  
  \section {Introduction}
  Introduction is written here, but not relevant for this question.
  
  
  \section {Background} 
  Here I write some text and refer to an article of Draganovic from 2013 \citep{Draganovic2013}. \\
  In another section, I would like to refer to Irungu from 2019 \citep{Irungu2019}.\\
  Current project will investigate the possibilities to re-evaluate Sustainable Fiber Technology's Wheat Straw Co-Product, by using it as a (partial) replacement of wheat gluten and/or starch in aquafeed. Being relatively high in lignin (20 - 40\% based on 30 - 50\% solids), the product is a potential excellent binder.
  
  \section {Rest of the document}
  
  Doesn't pose any significant errors.
  
   \bibliographystyle{plainnat}
   \bibliography{C://Users/Marjanne/Documents/April8/library}
  
  
  
  
  \end{document}
  </code></pre>