I have a retail copy of TOH and bought Hinds from GetGames (it was a Steam key), who clearly said that the copy of Hinds I was buying from them would work with retail TOH. However, when I try to activate it, it says "please first activate the original product". I've installed, fully patched and played TOH, running it through Steam (not activated on Steam, just added to Steam) and Hinds won't install.
Does anyone know how to fix this? Is it possible to get this working?