[Donnchadh MacGarry]

Hi all,
I was registred for this race but when i pussed the join button and after loading show me a error message of "checksum failed". 
Somebody can tell me why?
Thanks!!

PD: Sorry for my english, i hope that you undenstand me. 

The track was a mod but you were able to register meaning you have downloaded it and installed in the past. What I reckon is that you probably had an older version of the track. I would always double check that you have the most recent version of a track before each race you do. The latest version of Sachsenring is v1.09 which came out on the 16th October of this year.

The other possibility is that you don't own all the cars in the series. The BMW is base game content, but the Alfa and Mercedes was in the Dream Pack 1 DLC. You need to own all the cars in a race event to be able to take part in AC.
Link: https://store.steampowered.com/app/34799...am_Pack_1/