[XeTeX] Package Bidi Error

[@@]

Hi

My main Tex file starts like this:

 \input{header.tex}
\begin{document}
\begin{arab}
\begin{center}
\Huge \center \titlefont  {poem}
\author{me}
\end{center}
\begin{traditionalpoem}\bodyfont
\end{traditionalpoem}
\end{arab}
\end{document}


when header.tex is:

\documentclass{article}
\usepackage{fontspec}
\usepackage{geometry}
\geometry{ hmargin=2.5cm, vmargin=2cm }

\newfontfamily\titlefont[Script=Arabic]{KacstFarsi}
\font\titlefont="KacstFarsi:script=arab" at 48pt
\newfontfamily\bodyfont[Script=Arabic]{Scheherazade}



\usepackage[RTLdocument]{bidi}
\usepackage{bidipoem}
\usepackage{bidi}
\usepackage{xltxtra}
\usepackage{polyglossia}
\setdefaultlanguage{english}
\setotherlanguage{arabic}
\usepackage{arabxetex}
\setmainfont{Lucida Grande}
\renewcommand\poemcolsepskip{1.5cm}


But I have this error:
Package bidi Error: Oops! you have loaded package amsmath after bidi
package. Please load package amsmath before bidi package, and then try to
run xelatex on your document again.

Any help?


Regards
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