Hi there, I'm getting this message when trying to activate my key:
The product code you've entered requires ownership of another product before activation.

If you are trying to activate an expansion pack or downloadable content, please first activate the original game, then activate this additional content.

Did you perhaps put the wrong key in? ^^

Just like the other winner I'm getting the message:

"The product code you've entered has already been activated by a different Steam account. This code cannot be used again. Please contact the retailer or online seller where the code was purchased for assistance."

Any chance you have the real key?