Define various Trim size through a .sty file

I’m trying to write a package, which can supports various Trim sizes through option in TeX application file, and my tags are follows:

Definition in my .sty file

newififsixbynine  
newififsevenbynine
newififeightbynine

NeedsTeXFormat{LaTeX2e}

usepackage[a4,center,cam,info]{crop}

usepackage{lipsum}

ifsixbynine
setlength{paperheight}{9truein}%
setlength{paperwidth}{6truein}%
fi

ifsevenbynine
setlength{paperheight}{9truein}%
setlength{paperwidth}{7truein}%
fi

ifeightbynine
setlength{paperheight}{9truein}%
setlength{paperwidth}{8truein}%
fi


addtolengthtopmargin{-1in}

setlengthtextwidth{26pc}

setlengthtextheight{39pc}

setlengthoddsidemargin{5pc}
addtolengthoddsidemargin{-1in}    % subtract out the 1 inch driver margin
setlength@tempdima{paperwidth}
addtolength@tempdima{-textwidth}
addtolength@tempdima{-5pc}
setlengthevensidemargin{@tempdima}
addtolengthevensidemargin{-1in}

DeclareOption{6x9}{globalsixbyninetrue}
DeclareOption{7x9}{globalsevenbyninetrue}
DeclareOption{8x9}{globaleightbyninetrue}

ProcessOptions

endinput

Content of my .tex file

documentclass{book}
usepackage[6x9]{test}

begin{document}

lipsum[1-9]

end{document}

But the output doesn’t come what I expected. Can you help me what I did wrong in my definitions…