Activating Steam Games.

I bought a few games in the stores before they were available in Steam and now I would like to make it so I use them through Steam. So I go to activate the key but it says invalid... I'm sure I typed it right because I copy/pasted and it still says invalid... Can I not activate a store bought version of a game in Steam? (Games trying to activate: Company of Heroes, Stalker, Far Cry, and Bioshock).

Thanks for the help!

Ya I've done that before adding a none Steam game like that... Just adds the shortcut.DiabeticDood

Unfortunately, I think that's as much as you can do. But I may be wrong so don't take my word for it.

BTW, who's this Buster?

Here it is guys:

All retail Valve games and a number of third-party games can be registered to your Steam account. All of the following games can be registered through Steam:

Valve CD Keys in this format: ####-#####-####

Valve CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q

Alpha Prime, Dark Messiah, GTI Racing,GTR Evolution, Lost Planet: Extreme Conditions,NBA2K9,Prey, E7RACE - the WTCC, RACE 07, Ragdoll Kung Fu, Red Orchestra, SiN Episodes: Emergence, The Ship, STCC.

Opposing Force CD-keys cannot be registered through Steam. Opposing Force was included in a retail Half-Life package. The Half-Life CD-key included in the package will unlock all of the games in that package, including Opposing Force.

Note: Only the retail third-party games listed above can be registered through Steam. No other third-party games can be registered and downloaded using Steam.