Thank you, Dennis, for replying. I think the dratted thing disappeared. I tried to post the link to it on the question, but it wouldn't finish the question with it there, so I guess I was doing it wrong. Anyway, I understand that I need to message the person, but it never gave me a name. It just said that someone had her as living, while I was trying to post her as deceased.
I suppose it could be me that has a profile already for her, but on my homepage, it shows my tree as empty (or it did, anyway, before I added my mother. At any rate, it seems like I never put up a profile for her in the past...)