Problemi con bibtex: found no citation commands

Ciao, è la prima volta che scrivo su questo forum.
Ho iniziato da poco ad usare latex (come editor uso texworxs) e da ieri sera sto cercando di risolvere un problema con la bibliografia.
Ho caricato tutti i pacchetti del caso, creato il mio database .bib, compilato il documento con latex, con bibtex e poi di nuovo due volte con latex.
Il problema è che nel documento finale non compare alcuna bibliografia e che al posto delle citazioni compaiono le etichette dei miei riferimenti bibliografici.
Quando compilo con latex appaiono questi warnings:
tesi.tex
Package Fancyhdr Warning: \headheight is too small (12.0pt):
LaTeX Warning: Citation ‘bibliografia/tresch:compares’ on page 5 undefined on input line 58.
LaTeX Warning: Citation ‘bibliografia/tresch:compares’ on page 13 undefined on input line 133.
LaTeX Warning: Citation ‘bibliografia/clark:mergsyn’ on page 13 undefined on input line 134.
LaTeX Warning: Citation ‘bibliografia/torres:subspec’ on page 13 undefined on input line 134.
LaTeX Warning: Citation ‘bibliografia/mucelli:synmat’ on page 13 undefined on input line 134.
LaTeX Warning: Empty bibliography on input line 35.
LaTeX Warning: There were undefined references.
Package biblatex Warning: Please (re)run Biber on the file: tesi and rerun LaTeX afterwards.

quando compilo con bibtex appare:
This is BibTeX, Version 0.99d (MiKTeX 2.9)
The top-level auxiliary file: tesi.aux
I found no \citation commands—while reading file tesi.aux
I found no \bibdata command—while reading file tesi.aux
I found no \bibstyle command—while reading file tesi.aux
(There were 3 error messages)

e compilando ancora con latex rimangono gli stessi warnigns…
Ho cercato dappertutto una soluzione e ho visto che altre persone si sono trovate di fronte a questo problema, ma io ho fatto tutto quello che hanno fatto loro e il problema persiste…non so proprio come fare.

IL codice sorgente che ho usato è questo:
`% !TEX encoding = UTF – 8
% !TEX program = pdflatex
% !TEX spellcheck = it_IT

\documentclass[a4paper, 12 pt]{book}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[english, italian]{babel}

\input{tesipackages}

\begin{document}

\tableofcontents

\frontmatter

\mainmatter
\input{capitoli/cap1}
\input{capitoli/cap2}
\input{capitoli/cap3}
\input{capitoli/cap4}

\backmatter
\cleardoublepage
\phantomsection
\addcontentsline{toc}{chapter}{\bibname}
\nocite{*}
\printbibliography

\end{document}`

i pacchetti caricati sono:
`
% !TEX encoding = UTF – 8
% !TEX program = pdflatex
% !TEX spellcheck = it_IT

%pacchetti base
\usepackage{etoolbox}

\usepackage[babel]{csquotes}
\usepackage[style=numeric-comp,useprefix,hyperref,backend=biber]{biblatex}

\bibliography{bibliografia}
\usepackage{hyperref}
\usepackage[output – decimal-marker ={,}]{siunitx}
\usepackage{times}
\usepackage{graphicx}
\graphicspath{immagini}
\usepackage{caption}
\usepackage{subfig}
\usepackage{float}
\usepackage{appendix}
\usepackage{booktabs}
\usepackage{longtable}
\usepackage[dvipsnames,usenames]{color}
\usepackage{indentfirst}
\usepackage{amsmath,amssymb}
\usepackage[italian]{varioref}
\usepackage{microtype}
\usepackage{array}
%impostazioni personali
\captionsetup{format=hang,labelfont={sf,bf}, font=small}
\usepackage[a4paper,top=3cm,bottom=3cm,left=4cm,right=3cm]{geometry}
\usepackage{setspace}
\onehalfspacing
\usepackage{fancyhdr}
\pagestyle{fancy}
\renewcommand{\headrulewidth}{0pt}
\fancyhead[LO,RE]{}
`

per le citazioni ho usato \cite{bibliografia/etichetta}
dove bibliografia è la cartella contenente il mio file .bib. ho provato anche semplicemente con \cite{etichetta} ma il problema è identico.
il mio database bibliografico è questo:
`

@article{clark:mergsyn,
author = {Clark, D.J. and Ting, L.H. and Zajac, F.E. and Neptune, R.R. and Kautz, S.A.},
title = {Merging of healthy motor modules predicts reduced locomotor performance and muscle coordination
complexity post-stroke},
journaltitle = {J Neurophysiol},
number = {103},
pages = {844-857},
date = {2010}
}

@article{cheung:cortdamage,
author = {Cheung, V.C.K. and Turolla, A. and Agostini, M. and Silvoni, S. and Bennis, C. and Kasi, P. and Paganoni, S. and Bonato, P. and Bizzi, E.},
title ={Muscle synergy patterns as physiological markers of motor cortical damage},
journaltitle = {PNAS},
volume = {109},
number ={36},
pages = {14652-14656},
date = {2012}
}

@article{avella:shared,
author = {d'Avella, A. and Bizzi, E.},
title = {Shared and specific muscle synergies in natural motor behaviors},
journaltitle = {PNAS},
volume = {102},
number = {8},
pages = {3076-3081},
date = {2005}
}

@article{neptune:modular,
author = {Neptune, R.R. and Clark, D.J. and Kautz, S.A.},
title = {Modular control of human walking: a simulation study},
journaltitle = {Journal of Biomechanics},
number = {42},
pages = {1282-1287},
date = {2009}
}

@article{avella:comb,
author ={d'Avella, A. and Saltiel, P. and Bizzi, E.},
title ={Combinations of muscle synergies in the construction of a natural motor behavior}
journaltitle = {nature neuroscience},
volume = {6},
number = {3},
pages = {300-308},
date = {2003}
}

@article{tresch:compares,
author = {Tresch, M.C. and Cheung, V.C.K. and d'Avella, A.},
tilte = {Matrix factorization algorithms for the identification of muscle synergies: evaluation on simulated and experimental data sets},
journaltitle = {J Neurophysiol},
number = {95},
pages ={2199-2212},
date = {2006}
}

@article{lee:nmf,
author = {Lee, D.D. and Seung, H.S.},
title = {Learning the parts of objects by non-negative matrix factorization},
journaltitle = {Nature},
volume = {401},
pages = {788-791},
date = {1999}
}

@article{lee:algo,
author = {Lee, D.D. and Seung, H.S.},
title = {Algorithms for non-negative matrix factorization},
journaltitle = {Neural Inform Proc Syst},
number = {13},
pages = {556-562},
date = {2001}
}

@article{tresch:forandagainst,
author = {Tresch, M.C. and Jarc, A.},
title = {The case for and against muscle synergies},
journaltitle = { Curr Opin Neurobiol},
number = {19},
pages = {601-607},
date = {2009}
}

@article{bizzi:comb,
author = {Bizzi, E. and Cheung, V.C.K. and d'Avella, A. and Saltiel, P. and Tresch, M.C.},
title = {Combining modules for movement},
journaltitle = {Brain Res Brain Res Rev},
number = {57},
pages = {125-133},
date = {2008}
}

@article{mucelli:synmat,
author = {Mucelli, S. and Boye, A.T. and d'Avella, A. and Farina, D.},
title = { Identifying representative synergy matrices for describing muscular activation patterns during multidirectional reaching in the horizontal plane},
journaltitle = {J Neurophysiol},
number = {103},
pages = {1532-1542},
date = {2010}
}

@article{torres:subspec,
author = {Torres-Oviedo, G. and Ting, L.H.},
title = {Subject-specific muscle synergies in human balance control are consistent across different biomechanical contexts},
journaltitle = {J Neurophysiol},
number = {103},
pages = {3084-3098},
date = {2010}
}
`

grazie in anticipo
Debora