Little Sister disappeared?

[georgiadude330]

I'm in Siren Alley, and when I was running around with a Little Sister to gather Adam, I ran in to a Big Daddy who also had a Little Sister. When I came back, my Little Sister was crying, so I readopted her but had to gather twice (I had already gathered once). Now, I've completed the level, except for one Little Sister. I keep running to 3 different spots where Big Daddies are, and they beat on the vents to no avail. No Little Sister will come out. Any help? Any tips? Surely that interaction that I had wouldn't keep a third little sister from coming out, would it?