Disc 2 forza 4 not install

Hello all well

I am having problem with the forza 4 Disc 2
When I start the disc 1 and put in order to install the DLCs of the disk 2 cars it error

wrong disc
insert Disc 2

I already have this game is 3 years and usually settled until one year ago there took to play again and is giving this error

Delete the Forza 4 content off your Xbox 360 hard drive, backup your save if you haven’t already.

  1. Insert Disc 2 (Content Disc).
  2. Make sure you are online just in case it needs a title update.
  3. Install content disc.
  4. Then insert play disc.

MOVE your save, NEVER EVER backup a Forza save.