为什么参考书目是空的？

Question

我使用 TeXnicCenter。使用 Legrand Orange Book（LaTeX 模板，版本 2.2（30/3/17）），编译参考书目时显示为空。

有关参考书目使用的命令如下。

1）主文件：

\chapterimage{}
\chapter*{Bibliografia}
\addcontentsline{toc}{chapter}{\textcolor{ocre}{Bibliography}}
\section*{}
\addcontentsline{toc}{section}{Books}
\printbibliography

2）结构：

\usepackage[style=alphabetic,citestyle=numeric,sorting=nyt,sortcites=true,autopunct=true,babel=hyphen,hyperref=true,abbreviate=false,backref=true,backend=biber]{biblatex}
\addbibresource{bibliography.bib} % BibTeX bibliography file
\defbibheading{bibempty}{}
\usepackage{calc} % For simpler calculation - used for spacing the index letter headings correctly
\usepackage{makeidx} % Required to make an index
\makeindex % Tells LaTeX to create the files required for indexing

3)参考书目

@book{book_key,
    address = {Boston},
    publisher = {Birhäuser},
    author = {Andreecu,Titu; Gelca, Razvan},
    title = {Mathematical Olympiada Challenges},
    year = {2009},
    volume = {1},
    series = {},
    edition = {1},
    pages = {},
    month = {}
}

@book{book_key,
    address = {Rio de Janeiro},
    publisher = {SBM},
    author = {Morgado, A C de O; Carvalho, J B P; Fernadez, P},
    title = {Combinatória e Probabilidade},
    year = {2004},
    volume = {},
    series = {},
    edition = {2},
    pages = {},
    month = {}
}