I am using Maple 12 on Windows XP.  When I export a plot to postscript as follows

plotsetup(ps,`filename.eps`,plotoptions=`width=2in,height=3in`);
plot(...);

the width and height options seem to have no effect.   The graphic is always 19.579 cm by 19.579 cm.  Other options such as portrait and noborders do have an effect.  Any suggestions for why this is not working?