Hello everyone

First of all, I'm very sorry for my grammar - please don't laugh at my mistakes because English is not my mother language.
I have a very strange problem with my game and, unfortunately, have no idea how to solve it. Yesterday my sim celebrated her birthday and became an elder. Everything seemed ok, but when I turned off my game and came back to play it later, my sim was young again (despite the fact that the line which shows the age of the sim said she was an elder) ! And such strange things happen not only to elders, but also to teenagers...
I would be very, very glad if you could help me. Thank you