Leo Wagner: I had the same issue. I suppose it's because now white's group has only one liberty and can instantly be killed.
caranthir: Yeah, it seems that the problem has been modified. If there were an extra liberty, then I'd usually prefer Fergalicious's sequence, since the remaining ko threat (if not ate-connect-take first) is bigger for the attacker.
Fergalicious: Sequence wC1,bD1,wC2,bF1,wA1 gives the same result but removes a ko threat which could be used by either player. I may be wrong, but is this not a successful result also?
Yeah, it seems that the problem has been modified. If there were an extra liberty, then I'd usually prefer Fergalicious's sequence, since the remaining ko threat (if not ate-connect-take first) is bigger for the attacker.