I have solved part of the problem - I can only set two of the walls to solid fill - both the Stucco ones. I changed all to solid fill and inserted all into one model - only the two Stucco ones come out solid. I will now try using these to re-create the other walls and may then get them all to fill.
However that has not solved my tracing problem - even with the stucco walls showing solid, they do not show through the trace image. I thought it may be just an isse on my laptop (Win 2000 ATI graphics I think), so I have now installed it on my desktop (Win XP with Nvidia graphics) but it is exactly the same. Only Stucco walls can be set to solid and they still do not show through the image with dimming tried from 5% to 95%. I wonder why this works for others and won't on either of my PC's?
Have you tried an image in a mirror on the floor in TFP as you did in previous versions? Presumably it should work.