Grandma’s Comfort Soup doesn’t work?

Maybe they caught the flu again or is it immediate? Is someone else in the household also sick? I know I was playing a home for kids and I had to lock them in separate rooms or they all kept getting sick and the lady who ran the place. Custom foods might be a problem, too. TS2 is also funny in some ways if anyone cheats certain things (don't know how anyone could cheat comfort soup) where it won't count if it got cheated into the gameplay. Like getting the last skill of anything will never count (or at least didn't used to when it was the discs.) Don't know if you mean right away but don't allow any townies on the lots until they are all cured. But townies spread it but I would guess some custom plate/food. Since it should work and not get the message again unless the Sim next to them is also sick.