Sounds like you didn't engage the target like th above poster mentioned, of course it'll say "Pickpocket" but the two options for Feed/Pickpocket appear when you press/click them. Hope that settles that, also I never knew you couldn't feed on other vampires so yeah, why would they sleep anyways when the townsfolk are all dreaming away, like helpless cattle! >:D
Im a hybrid (werewolf and vampire at the same time) thanks to the Ring of Hircine. I am still able to feed as a werewolf but still cant get the option to show up to feed as a vampire while im sneaking up on someone as they are sleeping. Maybe it has something to do with the ring of hircine being equipped. I am at stage 4 of Vampirism and every one attacks me on sight. I know how to feed as a normal vampire, i did it with another character, but its not working with this character and Im really starting to be leave this is a bug. Guess I should have just stayed as a werewolf.
Just so you know, you can't actually be a werewolf and vampire at the same time. The Ring of Hircine only works if you have Lycanthropy. Just having the ring doesn't make you a werewolf. --- If you are interested in an ES Roleplay story go to the board in my quote