Counter Strike Source key Already in use wtf?

[Bomil75]

So yeah i decided to buy counterstrike source,
Came home and yes whenever i tried to activate the product it said
it was already in use by another existing account..
So i brought it back to the shop.. Got my money back and bought a new one from the same shop. Got home and YES STILL THE SAME ERROR...
IM so pissed off please someone help me :S am i doing somthing wrong or somthing? damn this

[Blinx]

i live in germany and theres also media markt, commercials ever 2 minutes of it etc...
well, usually it shouldnt happen
cause they "promise" that every thing they sell should work... if the game is already opened somebody may stole the key to play online o_o"

[Bomil75]

the game was packed in 2 times so there would be no way they could open it.
I guess some F@GS who cant afford the game used KEY generators ...
Im so angry at the moment it failed 2 times .. omg

[Deimos]

the game was packed in 2 times so there would be no way they could open it.
I guess some F@GS who cant afford the game used KEY generators ...
Im so angry at the moment it failed 2 times .. omg

do keygens do that? surely the odds of that would be like 1 in a zillion