pansonic Blu-ray Recorder sound problem

Hi i wonder if anyone can help in that when i record a TV program in BBC/ITV HD and burn it to a disc for archiving it will only playback on this recorder only with sound and vision. i can play it back on a computer and other blu ray players but then there is no sound :o despite the fact i have all the top main players available. does anyone know of what is wrong. Recording to disc in SD from the TV works well in all players and computer. it's a bit pointless archiving HD from the TV to disc only to find out in years to come that you will have no sound in playback
thanks in advance for any help here :)