I am trying to learn the Freemium version to decide if I should upgrade from OrCAD. I have followed the manual and set up the layers (1+2*15+16). Under the AutoRoute I select AUTO for the internal layers and let it rip. I average a completion rate for my SMD board of 98.4. With this said, it NEVER uses layer 15 for any routes. Layers 1, 2 and 16 all have routes. Am I missing something in the board setup that would prevent the Autorouter from routing via Layer 15?