I had a board that was 6 layer. After some changes I have managed to make
the board route in 4-layers quite readily. Then I went to delete the layers
from the layer display. It let me delete layer 4, but not layer 5.
Obviously something is still using layer 5, but it is not displayed. Is
there some way to find anything on this layer? I have tried turning off all
layers except 5 and see what is displayed. Nothing is displayed in this
case. My board design rules makes no reference to layer 5 and the router
setup make no reference to layer 5 either.
Thanks for listening,
Eldon R. Hiebert