I borught the Poirot Box set from amazon. When I put in two of the discs (Murder in the Sky and the Mysterious events at Stlyes). The machine came back cannot play the disc. It worked in the machine downstairs (pioneer 454)and after putting in about 6 r2 in the machine upstairs (pioneer 515 about 4 years old) it worked. Is the 515 getting past it or is it a problem with the disc.