using an A/V cable to hook up my Ipod to my TV! Needing Help? Please?

I have a video nano, and I keep reading that you can hook up to a tv through an AV cable but all I get is sound. Can someone tell me what to do. I also have an I home and I tried that but it was just sound as well. Please and thank you.
not the newest nano, but the one before it. Its square.
oh and when I set video-out to on it tells me to hook it up to video thing.
 
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