LaTeX: Extra page when using thmbox

% MWE corresponding following question: http://tex.stackexchange.com/q/182780/39090
% german comments removed!

% ======== main.tex File ========

\documentclass[
	a4paper,
	oneside,
	12pt,
	toc=listof,
	toc=bibliography,
]{scrreprt}%

\usepackage{styles/bachelor}

\begin{document}

\include{chapters/titelpage}

\pagenumbering{roman}

% ..........

\tableofcontents
\newpage

\pagenumbering{arabic}

% TEXT TEXT TEXT TEXT
% \include{} used

\nocite{*}
\bibliographystyle{plain}
\bibliography{bib/bibfile}

\end{document}

%% ======== bachelor.sty - File ========

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[ngerman]{babel}


\usepackage[
	autostyle,
	german=quotes
]{csquotes}
\usepackage{marvosym}

\usepackage{pifont}


\usepackage{setspace}
\onehalfspacing

\usepackage{scrhack}

\usepackage{array}


\usepackage{graphicx}
\usepackage{caption}
\usepackage{subfig}

\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{empheq}
\usepackage{dsfont}
\usepackage{amstext}
\usepackage{amsfonts}
\usepackage{amsthm}
\usepackage{wasysym}

\usepackage[S]{thmbox}

\usepackage{color}

\usepackage{listings}

\usepackage{algorithm}
\usepackage{algpseudocode}

\usepackage{parskip}

\usepackage{fancyhdr}

\usepackage{ifthen}

\usepackage[
	bookmarks,
	raiselinks,
	pageanchor,
	colorlinks,
	citecolor=black,
	linkcolor=black,
	urlcolor=magenta,
	filecolor=cyan
	menucolor=red,
]{hyperref}

\usepackage[
	left=3cm,right=2.5cm,top=1.5cm,bottom=1.5cm,
	headheight=7mm,headsep=1.2cm,
	footskip=1.5cm,includeheadfoot
]{geometry}

\theoremstyle{plain} \newtheorem{lem}{Lemma}[section]
% ===========================================================================================================================
\theoremstyle{remark} \newtheorem*{rem}{Remarks and Extensions} %%%% HERE IS THE BUG!
% ===========================================================================================================================
\theoremstyle{plain} \newtheorem{thm}[lem]{Theorem}
\theoremstyle{definition} \newtheorem{defi}{Definition}
\theoremstyle{plain} \newtheorem{cor}[lem]{Corollary}

\DeclareMathOperator*{\argmin}{\arg \min}%

\pagestyle{fancy}

\renewcommand{\chaptermark}[1]{
	\markboth{\thechapter \quad #1}{}}

\ifthenelse{\boolean{@twoside}}
{
	\fancyhf{}
	\fancyhead[RO,LE]{\small\sffamily\bfseries\thepage}
	\fancyhead[LO]{\small\sffamily\nouppercase{\leftmark}}
	\renewcommand{\headrulewidth}{0.4pt}
	\renewcommand{\footrulewidth}{0pt}
	\fancypagestyle{plain}{
		\fancyhf{}
		\fancyhead[RO,LE]{\small\sffamily\bfseries\thepage}
		\renewcommand{\headrulewidth}{0.4pt}
		\renewcommand{\footrulewidth}{0pt}
	}
}
{
	\fancyhf{}
	\fancyhead[R]{\small\sffamily\bfseries\thepage}
	\fancyhead[L]{\small\sffamily\nouppercase{\leftmark}}
	\renewcommand{\headrulewidth}{0.4pt}
	\renewcommand{\footrulewidth}{0pt}
	\fancypagestyle{plain}{
		\fancyhf{}
		\fancyhead[R]{\small\sffamily\bfseries\thepage}
		\renewcommand{\headrulewidth}{0.4pt}
		\renewcommand{\footrulewidth}{0pt}
	}
}