User blog comment:Dturpin48/Eve/@comment-1509826-20120827215015/@comment-2020973-20120827222036

It's not that she couldn't kill Crowley she just couldn't find him so thats why she was going to use Sam and Dean to do it. Remember when Edgar fought (well not really fought) those two angels, when he killed the first one the second tried to use his angel power on him but nothing happened. Also, Castiel was able to teleport into the town where Eve was but once he was there he wasn't able to teleport out.