Problem with biblatex - Cannot get simple specification to execute

Question

I am trying to replicate with biblatex a very simple specification that works with bibtex (but I want to migrate to biblatex because it's better).

This works fine (which proves as well that my .bib file has no errors):

\documentclass[11pt,a4paper]{article}
\usepackage{setspace}
\usepackage[a4paper,includeheadfoot,margin=2.54cm]{geometry}
\begin{document}
\title{\vspace{-2.54cm}Simple Test of \texttt{bibtex}}
\author{}
\date{}
\maketitle
Three items are cited:
\begin{itemize}
\item \textit{The \LaTeX\ Companion} book \cite{latexcompanion}
\item The Einstein journal paper \cite{einstein}
\item The Donald Knuth website \cite{knuthwebsite}
\end{itemize}
The \LaTeX\ related items are \cite{latexcompanion,knuthwebsite}.
\bibliographystyle{plain}
\bibliography{sample}
\end{document}

But this won't work:

\documentclass[11pt,a4paper]{article}
\usepackage{setspace}
\usepackage[a4paper,includeheadfoot,margin=2.54cm]{geometry}
\usepackage{biblatex}
\addbibresource{sample.bib}
\begin{document}
\title{\vspace{-2.54cm}Simple Test of \texttt{biblatex}}
\author{}
\date{}
\maketitle
Three items are cited:
\begin{itemize}
\item \textit{The \LaTeX\ Companion} book \cite{latexcompanion}
\item The Einstein journal paper \cite{einstein}
\item The Donald Knuth's website \cite{knuthwebsite}
\end{itemize}
The \LaTeX\ related items are \cite{latexcompanion,knuthwebsite}.
\printbibliography[title={References}]
\end{document}

The references are undefined. Anyone that can point out to me what I am doing wrong would be doing me a very great favour.

My sample.bib file, for what it's worth, is as follows:

@article{einstein,
    author =       "Albert Einstein",
    title =        "{Zur Elektrodynamik bewegter K{\"o}rper}. ({German})
        [{On} the electrodynamics of moving bodies]",
    journal =      "Annalen der Physik",
    volume =       "322",
    number =       "10",
    pages =        "891--921",
    year =         "1905",
    DOI =          "http://dx.doi.org/10.1002/andp.19053221004"
}
@book{latexcompanion,
    author    = "Michel Goossens and Frank Mittelbach and Alexander Samarin",
    title     = "The \LaTeX\ Companion",
    year      = "1993",
    publisher = "Addison-Wesley",
    address   = "Reading, Massachusetts"
}
@misc{knuthwebsite,
    author    = "Donald Knuth",
    title     = "Knuth: Computers and Typesetting",
    url       = "http://www-cs-faculty.stanford.edu/~{}uno/abcde.html"
}

Thanks!