Calling on the dead is different then requesting saints in heaven pray for you. If you call upon a spirit, more then likely it will be an evil one. You are then inviting the evil spirit into your life.
I guess I don’t see the difference. The dead are dead in body only, however, the spirit and soul live forever. How do you know if one is calling upon a so-called saint in heaven, or a demon from the pits of hades?