Trouble setting up my apple tv on my toshiba regza 32RV753 tv, it just doesn't work

Can anyone help with the above problem please. The TV is only 2 years old and has the required HDMI slots (4 in fact) I have the Apple TV cable plugged into HDMI 4 on the side of the tv.

No matter which of the slots I use the apple tv doesn't work. I'm guessing its a settings issue with the toshiba tv, can anyone help.

Totally frustrated my Saturday.

Ta