can't find the error

could somebody help me I can find the error

documentclass[preprint,3p,12pt]{elsarticle}

journal{Int. J. Appl. Comput. Math}

%------------------------------------------------------------------------------
usepackage[dvips]{epsfig}
usepackage{amsmath}
usepackage{amssymb}
usepackage{amstext}
usepackage{rotating}
usepackage{psfrag}
usepackage{color}
usepackage{epstopdf}
usepackage{stmaryrd}
usepackage{algorithmicx}
usepackage[ruled]{algorithm}

%==========================================
defds{displaystyle}
defgr#1{text{bf #1}}

DeclareSymbolFont{msbm}{U}{msb}{m}{n}
DeclareMathSymbol{R}{mathalpha}{msbm}{'122}
DeclareMathSymbol{N}{mathalpha}{msbm}{'116}
DeclareMathOperator{rand}{rand}
DeclareMathOperator{Pe}{Pe}

defrbf{RBF }

newcommand{bfx}{{bf x}}
newcommand{bfv}{{bf v}}
newcommand{D}{mathcal{D}}
newcommand{bfX}{{bf X}}

defRBF{RBF }
newcommand{I}{{mathcal{I}_{i,m}}}
newcommand{Ic}{{I_{i+1/2,m}}}
newcommand{Iu}{{I_{i,m}}}


newcommand{mI}{{I_{i+1/2,m}}}
newcommand{hI}{{widehat{I}_{i,m}}}


newcommand{Ip}{{I^+_{i,m}}}
newcommand{Imn}{{I^-_{i,m}}}

parskip1ex plus1ex minus1ex
%==========================================


begin{document}
All we know is limited, apart from knowing cite{Micchelli} the answer we all know.Some people are too cite{Hosseini}nosy. What can happen to them (figure ref{s}) is described by Laura Lion~auto{glass2012}.
bibliographystyle{plain}
bibliography{Biblio}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
end{document}