No sound from wireless speakers

Hi,
I have the sc-pt 850W home theatre system. The system worked fine for 4 months and all of a sudden, the rear wireless speakers are not connecting to the head unit. The red W1 on the head unit flashes for a while and then turns off and the green light never comes on to the wireless box that the rear speakers are connected to. I thought it may be the signal, but I put the wireless box on top of the head unit and that didn't work. I checked all connections etc.
Any ideas.