Sorry, I didn't realise from your post that the key was already activated (I thought you were saying you activated it). I received this in the Groupees "Tax Year 3" bundle, and had no idea it was previously activated. Apparently this has been a problem with "Eryi's Action" keys in the past: https://www.steamgifts.com/discussion/y7iZo/warning-eryis-action-steam-keys-are-not-working

I will contact Groupees and see if I can get a replacement.