iOS to TV

I have an iPad 3, I bought a composite wire (Red, White and Yellow) to 30 pin iOS.

I connected it up to three seperate TVs but only the sound would work on the TV, no picture. Same story for all three TVs.

I tried changing the 'TV Out' settings on the iPad to both Widescreen on and off, then both PAL and NTSC, as well as combinations of those options.

The only thing I can think of (apart from the possibility of a bad wire, of course) is that maybe one of the audio (Red and White) wires is actually the Video (Yellow) wire, but just wired up wrong perhaps. I don't know.

Any suggestions would be appreciated, thanks.