Bibliography and \cite{} in different files; problem when compiling master file

Question

I am writing my dissertation in LaTeX and as it's a long document I have split up the chapters into separate .tex files and am compiling them from a master .tex file:

\documentclass[]{report}
\usepackage{mystyle}
\begin{document}
%front matter
\input{./tex/title.tex}
\input{./tex/abstract.tex}
\tableofcontents
%main matter part 1
\input{./tex/pt_tru.tex}
\input{./tex/ch_itb.tex}
\input{./tex/ch_mech.tex}
\input{./tex/ch_lag.tex}
\input{./tex/ch_tbp.tex}
\input{./tex/ch_kepler.tex}
%main matter part 2
\input{./tex/pt_snc.tex}
\input{./tex/ch_nt.tex}
\input{./tex/ch_conslaws.tex}
%back matter
\input{./tex/ch_appa.tex}
\input{./tex/ch_litrev.tex}
\input{./tex/ch_addlit.tex}
\input{./tex/ch_ack.tex}
\end{document}

In the addlit.tex file I am calling the bibliography:

\renewcommand{\bibname}{Additional Literature}
    \addcontentsline{toc}{chapter}{Additional Literature}
    \bibliography{dissbib.bib}
    \bibliographystyle{unsrt}

And in various other chapters e.g. itb.tex I am citing things from that bibliography:

"...necessitating the use of the theory of general relativity \cite{Roseveare}."

My problem is that when I compile the master .tex file, the citation appears as [?] and the section with the heading "Additional Literature" is blank. How can I solve this problem so that the citations are correct and the bibliography appears?

I am using TexStudio and Bibtex, if that makes any difference.

Edit: my .sty file is

\ProvidesPackage{mystyle}
\usepackage{listings} 
\usepackage{enumitem} 
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{parskip} 
\usepackage{graphicx} 
\graphicspath{ {images/} }
\usepackage{mathtools} 
\usepackage{float} 
\usepackage{wrapfig} 
\usepackage{cite}

My .bib file is like this:

@book{Roseveare, 
author= {Roseveare, N. T.},
year=1982,
title= {Mercury's Perihelion from Le Verrier to Einstein},
publisher= {Oxford University Press},

}

and my .tex files are like this:

\chapter{title}
\section{title}
Some text here. Some text here. Some more text here \cite{Roseveare}.

Answer 1

Don't mention the filename extension .bib in the argument of \bibliography. The instruction should be

\bibliography{dissbib}

rather than \bibliography{dissbib.bib}.