LizzieRossetti: Pity, because I have the ability to prove an exceptional exception to that particular rule.
That she does!
If I may interject, I think the OP was saying the marker said 12 inches uphill when it was really 12 inches downhill. And to be honest, I have thought that a few times too. Granted, I may have misread it, but only a few days ago I was sure I'd read one way and it was actually the other.
Two problems here:
1) In a multi-player game you cannot save a replay as someone suggested.
2) You don't always realise it is wrong until after you have hit the putt, and because the marker then disappears, there is no way of knowing whether you read it wrong or whether WGT displayed it wrong.
I'm guessing if this is an error, it will most likely stay with us forever.