your routing is not set for ADAT!
Try loading any odf the ADAT pre_made factory routings by pressing and holding the PROGRAM key. This will let you get into the routing area where you can load routing #12 or #19. This will make the difference. If you want to also use the Echoplex via analog input, you'll then need to modify the loaded routing to accomodate the analog input. The MAIN inputs and outputs are what really make the connection from/to the outside world.
all the best