No legal cars (Forza Motorsport 4)

Yes. You know, I'm a very old man and play Forza 4 in 2017.
(I wonder, are there more?)
LVL 31, series masters race 3 of 17, road Atlanta, get out the window No legal cars.
And there is the type you need to buy a car to continue in the global tournament.
Help plz, and something like that is not cool at all
=((