The claim is that Linda and Terry Jamison are psychic. They make predictions and publish books where they commune with the deceased.
As a skeptic, I can't help but think that one lucky guess on a major event, (the destruction of the world trade center by terrorists), has launched their careers and now they make fairly safe and vague predictions. The communing with the dead could also be done by properly doing their research and taking the time to write the book well from the dead person's potential point of view. (but I have no proof)
What evidence is there that they are not psychic?
Meaning that they are not actually speaking to the dead for their books, and are unable to tell the future.