My Cd Key Wont Work On Steam

plgratton59

hi. ive installed steam i have an account. but when it ask me to type in my cd key it says my cd key is already been registered to an existing steam account and is invalid my subscription to HL platinum pack has not been completed. i own the game now for 2-3 years and they only person i gave my cd key is to my brother who it does the same thing to him when he tries to register to steam. help me please. i want to play ns 3.0!!!!!!!!!!!!!!!!!!!!!!!!!

sawce

<a href='http://www.steampowered.com/forums' target='_blank'>http://www.steampowered.com/forums</a>

NS does not and cannot control anything related to CD keys and Steam accounts...