RGB Scart Problem

[Spaceboy]

I've just gone a bought a dreamcast and RGB cable. On my two Tv's upstairs I get sound, but there is no video (although you can just about make out the dreamcast logon screen).

On the TV downstairs, I get a picture, but the colour's messed up (the logon screen come up pink).

I'm guessing it may just be a dodgy cable. Any other suggestions?