it should say quif the potion , but becoming a vampire requires you to be consumed by the flying purple creature which comes for you shortly , don't kill it and it should say that you are now a vampire
Batty cannot be killed. All you have to do is drink the rainbow colored juice potion with Q. It is called "good juice". Soon after drinking it, Batty will arrive to suck you dry and turn you into a vampire. Hope this helps!