I purchased all three games together. So I have all three serial numbers. I successfully registered and beat penumbra overture, but all this time didn't register the other two because I hadn't gotten to them yet. So now, I type in the registration code, I've checked it countless times (I saved the page with the purchases as a PDF so I know they are correct) but it just always resets to 000000000 when I click "validate". And when I exit it tells me "error, incorrect registration code". Could the long wait since purchase to register be at fault?
Tell me what possible causes there could be... is there some proof I can send you that I purchased the game?
Make sure the serials really are correct, that you are using the serials and not the download codes. Perhaps you enter O when it should be 0? The serials does not have a time limit or anything like that.