natbib package downloaded through miktex but not found after compiling

Question

I am completely new to doing bibliography and watched a youtube video about it. Downloaded JabRef, filled out the list for an article, saved it to the tex.file location, went to TexStudio and wrote \citep(article) using \usepackage{natbib}, \bibliographystyle{plainnat}, \bibliography{file from JabRef}. There are several warning messages and I do see in the code that the natbib package is not found. The citation is not done; only [?], which is strange at all because the citep style would give (Author et al, year) and thus I expect (?). And Also there is nothing in the reference section. Where is the problem?

\documentclass[a4paper,oneside,abstracton]{scrartcl}

\usepackage[utf8]{inputenc}
%\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}

\usepackage{natbib}

\usepackage[ngerman]{babel}
%\usepackage{caption}
\addto\captionsngerman{                         
   \renewcommand{\contentsname}{\textrm{Table of Contents}}}
%wird verwendet damit im Inhaltsverzeichnis der englische Name kommt

\usepackage{amsmath,amssymb,amsthm,amsfonts,amsbsy,latexsym}
\usepackage{wasysym} %astronomical symbols
%\usepackage[version=3]{mhchem} %Chemie-Package
\providecommand{\e}[1]{\ensuremath{\times 10^{#1}}}
%\usepackage{dsfont}
%\usepackage{enumerate,url}
\usepackage{graphicx}
\usepackage{a4wide}
\usepackage{titling}
%\renewcommand{\contentsname}{Table of Contents} %funktioniert nur wenn babel nicht verwendet wird.
\usepackage{booktabs}
\usepackage{lscape}
\usepackage{multirow}
\usepackage{subfigure}
\addto\captionsngerman{
    \renewcommand{\figurename}{Fig.}}
\usepackage{afterpage}
\usepackage{gensymb}
\usepackage{soul}
\usepackage{array}
%\usepackage{subcaption} %cannot be used with subfigure
%\setcounter{secnumdepth}{4}
%\setcounter{tocdepth}{4}

%% Control the fonts and formatting used in the table of contents.
%\usepackage[titles]{tocloft}

%% Aesthetic spacing redefined
%\setlength{\cftbeforechapskip}{}
%\setlength{\cftbeforesecskip}{0.5ex}


\begin{document}

\title{\LARGE Advanced Lab Course \\ [1em] \huge \textbf{xyz}}
\author{Hans Muster \hspace{1cm} Muster Hans}
\date{\\[1em] {September 2014} \\ [0.8cm] Supervisor Dr.
 \\ [0.5cm]  Institut \\ University behind the Moon}


\clearpage
\maketitle{}
\thispagestyle{empty} %Keine Seitenzahl auf erster (dieser) Seite %
\renewcommand\abstractname{\textrm{Abstract}}
\renewcommand\tablename{\textrm{Table}}
\addtokomafont{sectioning}{\rmfamily}
\newpage

\begin{abstract}
%\vspace{-0.25cm}
%\setlength{\parindent}{0pt}
blablabla
\end{abstract}

%\skip{}
\tableofcontents{}
\pagestyle{plain}
\newpage

\bibliographystyle{plainnat}
\bibliography{library}

\pagenumbering{arabic}
\section{Introduction}
\citep{Schamb2010}

\section{Theory}

\section{References}

\end{document}

Am I not allowed to make a section References because it is probably created automatically? When everything is working, I would like to configure everything that it is like in a paper such as this http://m.iopscience.iop.org/0004-637X/720/2/1691/pdf/0004-637X_720_2_1691.pdf where you are led to the reference at the paper end when clicking onto a cite and when clicking onto the reference at the end are led to the URL in the internet; also with colour coding.

---

TeXStudio code with corresponding .bib-entry code afterwards:

\documentclass[a4paper,oneside,abstracton]{scrartcl}

\usepackage[utf8]{inputenc}
%\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}

\usepackage{natbib}

\usepackage[ngerman]{babel}
%\usepackage{caption}
\addto\captionsngerman{
      \renewcommand{\contentsname}{\textrm{Table of Contents}}}
%wird verwendet damit im Inhaltsverzeichnis der englische Name kommt

\usepackage{amsmath,amssymb,amsthm,amsfonts,amsbsy,latexsym}
\usepackage{wasysym} %astronomical symbols
%\usepackage[version=3]{mhchem} %Chemie-Package
\providecommand{\e}[1]{\ensuremath{\times 10^{#1}}}
%\usepackage{dsfont}
%\usepackage{enumerate,url}
\usepackage{graphicx}
\usepackage{a4wide}
\usepackage{titling}
%\renewcommand{\contentsname}{Table of Contents} %funktioniert nur wenn babel nicht verwendet wird.
\usepackage{booktabs}
\usepackage{lscape}
\usepackage{multirow}
\usepackage{subfigure}
\addto\captionsngerman{
      \renewcommand{\figurename}{Fig.}}
\usepackage{afterpage}
\usepackage{gensymb}
\usepackage{soul}
\usepackage{array}
%\usepackage{subcaption} %cannot be used with subfigure
%\setcounter{secnumdepth}{4}
%\setcounter{tocdepth}{4}

%% Control the fonts and formatting used in the table of contents.
%\usepackage[titles]{tocloft}

%% Aesthetic spacing redefined
%\setlength{\cftbeforechapskip}{}
%\setlength{\cftbeforesecskip}{0.5ex}


\begin{document}

\title{\LARGE Advanced Lab Course \\ [1em] \huge \textbf{Impact}}
\author{abc \hspace{1cm} ABC}
\date{\\[1em] {September 2014} \\ [0.8cm] Supervisor Dr. 
 \\ [0.5cm] Physikalisches Institut \\ University behind the Moon}


\clearpage
\maketitle{}
\thispagestyle{empty} %Keine Seitenzahl auf erster (dieser) Seite %
\renewcommand\abstractname{\textrm{Abstract}}
\renewcommand\tablename{\textrm{Table}}
\addtokomafont{sectioning}{\rmfamily}
\newpage

\pagenumbering{roman}
\vspace*{120pt}
\begin{center}
blablabla
\end{center}
\newpage

\begin{abstract}
%\vspace{-0.25cm}
%\setlength{\parindent}{0pt}
blablabla
\end{abstract}

%\skip{}
\tableofcontents{}
\pagestyle{plain}
\newpage

\bibliographystyle{plainnat}

\pagenumbering{arabic}
\section{Introduction}
The mean mass density of the primordial solar nebula is estimated to have been $\mathord\sim10^{3} \; M_{\astrosun} \,\textup{pc}^{-3} < \bar{M} < \mathord\sim10^{4} \; M_{\astrosun} \,\textup{pc}^{-3}$ \citep{Schamb2010}.\footnote{corresponding to a central nebula density of $\mathord\sim10^{4} \; M_{\astrosun} \,\textup{pc}^{-3} \stackrel{\sigma=60\%}{<} M_{central} \stackrel{\sigma=95\%}{<} \mathord\sim10^{5} \; M_{\astrosun}\,\textup{pc}^{-3}$, whereas the percentage values indicate the confidence level to which the associated relation is valid}

\section{Theory}
\section{Instrumentation}
\section{Measurements}
\section{Results}
\section{Discussion}
\section{Conclusion}
\section{Acknowledgement}

%\section{References}
\bibliography{library}

\end{document}

.bib-entry:

% This file was created with JabRef 2.10.
% Encoding: Cp1252


@Article{Schamb2010,
  Title                    = {Properties of the Distant Kuiper Belt: Results from the Palomar Distant Solar System Survey},
  Author                   = {(Megan E.) Schwamb and (Michael E.) Brown and (David L.) Rabinowitz and Darin Ragozzine},
  Journal                  = {The Astrophysical Journal},
  Year                     = {2010},

  Month                    = {September},
  Number                   = {2},
  Pages                    = {17},
  Volume                   = {720},

  Abstract                 = {},
  Doi                      = {10.1088/0004-637X/720/2/1691},
  Owner                    = {},
  Timestamp                = {2014.09.21},
  Url                      = {http://m.iopscience.iop.org/0004-637X/720/2/1691/pdf/0004-637X_720_2_1691.pdf}
}