export tex format



the command :
tex(f,"f\:\\MATH\\maxima\\totomax\.tex"); give good result : the file 
totomax.tex exist with the good tex lines

myfile:\"f\:\\MATH\\maxima\\totomax\.tex\";
or myfile:\"f\\\:\\\\MATH\\\\maxima\\\\totomax\\\.tex\";

and
tex(f,myfile);

give result false in the command line of maxima, but the file does not 
exist of the harddisk !

I run with Windows XP !

Thank's for help

Daniel