Dashed lines in model space plot as solid line autocad lt 2012

Hi

I have been trying every thing that I can find online regarding this problem.  I have drawn a site plan in model space at 1to1 scale.  I try to draw hidden lines to show demolition.  In paper space the scale is set to 1"=50" to fit on paper.  But all the hidden lines plot solid.  I had changed LTSCALE,  PSLTSCALE,  to 1. This problem keeps happening in most every thing I draw.

Thanks