Well to me that reaction looked more like a "I was so close to a Test hundred! I'm a fool!". I'm very unsure on the Karthik dismissal, technology showed nothing, but fielders and umpire seemed convinced. I do remember Snicko at times not showing edges when the ball did hit the edge.
50-50 imo, we'll never know :X-files:
Karthik says he got a nick and he has no doubt about that. So I would give that to the umpire. The batsman has a better feel of the ball, and if he says there was a nick, I think it was.