TV fails to show programme details when "GUIDE" on remote is pressed

I have a Panasonic dvd recorder DMR-EX77 with a Panasonic TV TX37LZD81 and a Sky box. All worked well until a few days ago. Now the “GUIDE” on the dvd remote only results in a “No data” on the TV instead of details of the programmes. I have tried (I think) every combination of AV/TV/HTML with Drive Select and Input Select, and I have retuned the TV, with the same result. Everything else seems to work OK. I don’t think its an aerial problem, because I live in a modern purpose-built 84-apartment block of flats, and I haven’t heard of any problems with the neighbours reception. I need to use the dvd to record programmes, because there is only a single-aerial connection to the Sky box which therefore limits its use until a dual aerial can be fitted. I would be very grateful if anyone can advise me what the trouble might be and its solution.:frowning: