Hæ I do not know which version I have, but I have the PR,PB,Y sockets in the back. However when I go into the Connections menu I cannot choose it, I can only Choose PC.. Help is greatly appreciated in this matter

Hi All I just connected my Apple TV to Beovision 7. I am using the PR,Pb, Y connection on the back of the TV, but I only get sound, no image. I have gone to options -connections -AV4 :Source: PC, Audio 4 Then I have added the PC button into the LIST to watch it. I plugged the ATV into another TV and it got the image there. Can anyone advise on how to