I bought a new TV a couple of weeks ago. At first I couldn't get it to work through my BT vision box so I was just watching the built in Freeview including ITV 4 . Vision is up & running now but I can't get ITV 4 . I want to watch Brazil v Egypt on ITV 4 so I assumed if I just plugged the aerial into the TV rather than through the vision box I would be able to watch it. However it says No signal when I try . Why would this be when it worked before ?