Latex does not show my reference in the bibliography

I do not klnow why I am using bibliography but I cannot see the reference both in the text and in the section Reference. Here the code

documentclass[a4paper, 12pt]{article}
usepackage[UKenglish]{babel}
usepackage[scale=0.75]{geometry}
usepackage{xcolor}
usepackage{datetime}
usepackage{nomencl}
makenomenclature
usepackage{moreverb,url}

newcommandBibTeX{{rmfamily Bkern-.05em 
textsc{ikern-.025em b}kern-.08em
kern-.1667emlower.7exhbox{E}kern-.125emX}}
defvolumeyear{2016}
usepackage{graphicx,subfigure}

usepackage{nomencl}
makenomenclature
usepackage{setspace}

usepackage{natbib}


begin{document}
cite{Mayer}, cite{Oca} and cite{IEA}

section{Reference}

bibliographystyle{SageH}
bibliography{my_bibtex2}



end{document}

Here below my bblatex

@article{Mayer,
title = "User behaviour regarding natural 
ventilation – state of the art and
research needs",
journal = "9th Nordic Symposium on Building 
Physics - NSB 2011",
volume = "3",
author = "Mayer"
}


@article{Oca,
title = "Effect of thermostat and window opening 
occupant behavior models on energy use in 
homes",
journal = "Building Simulation",
author = "Oca"
}

@article{IEA,
title =   " Reliability of Energy Efficient 
Building Retrofitting-",
author = "IEA"
}

In the same folder of the script file I have SageH.bst

I cannot understand why I jusrt get question mark and the bibliography does not appear.

Any idea?