elminster_cs

Dear Obsidian, some years ago i bought KOTOR2 and i just notice that is now avaible on steam. I try to use my cd key on steam, but it tell me that is not avaible. I also ask steam about this, and they told me that the old cd key can't be redeemed. Why? I have bought it, why we are not allowed to redeem them? Is near to impobbile play without patch, but with steam we can have it again, i would like to play it again. Thanks a lot.