Well, my character finished the Dawnguard main quest. Joined the Volkihar, became a Vampire Lord and so on. Then I decided to cure my Vampirism. I cured it. After a few weeks of being a human, I wanted to become a Vampire Lord again. So I contracted my character with Sanguinare Vampiris on purpose, turned into a vampire. BUT, i can't turn into a Vampire Lord because I don't acquire the power to do so. Is this a bug or what? Can anyone help me?