Borderlands GOTY :(

Did you actually try activating the key? Also where did you buy it from?

The key format you post is a valid steam key. They're not all in the standard 15 character format.

Keys in that format can be activated on Steam.

Yeah, in summer i bought assassin's creed brotherhood ( phisical copy ) from some store at 10$ and it had invalid key -.-

1 check you put the correct key.
2 check the box info.
3 ask gearbox, not us :)

If i recall correctly, Borderlands 1 boxed can not be activated on steam. My friend had the same problem, its just not steam redeemable.

It's not a Steamworks game so that's why.

Your key is for retail copies only. I would recommend either trying to return it or just play it by adding a shortcut.