Autocad 04 Solid White Blocks Issue

I've made some window elevation blocks with a solid white (color
255,255,255) hatch backing, so when inserted into a drawing anything
behind my window block would not be seen or plotted. (ie. a window
inserted on an elevation with a brick facade. However I seem to run
into a problem when I plot the model space to a PLT file. All my
window blocks plotted black when I view the resulting PLT file. The
pen style I'm using is a modified monochrome.stb. I've attached the
following image of the modifications I made to the pen style --->>>
Any help
would be appreciated.