CD Key problem HEEEEEEEEEEEEEEEEEEEEEEEELP!!!!!

[Libuska-Villalobos]

After i login in Games For Windows LIVE it's says to enter my activation key...I entered the code but it says the key is invalid or the password is wrong...one of my friends told me he entered the activation key in Social Club when he started the game but i can't enter the code in Social Club because it's don't say to enter the code....Help me please i want to play so much multiplayer