I keep getting "invalid code" message

Does anyone know if there's a way to activate this game if I've never owned it in the past? I already have the GOTY version, but it would be cool to own the original version on Steam. So far all I've tried was a Games for Windows Live code which Steam didn't recognize as a valid code to add a game. It worked on Games for Windows Live, but not on Steam. I tried on Steam first. This was a code from the the original GFWL and not the GFWL GOTY version. I know you can still activate Batman: Arkham City on Steam...

I have the original Steam release and not the GOTY version of this game. I cannot get DLC anymore (no Harley) without essentially re-buying the game (the GOTY version). I also don't know if my version will get Steam Achievements and the removal of GFWL like the GOTY version is planned to have. If I am screwed on all counts I can promise that I will not be buying Arkham Origins when it is released and will just wait a while for the GOTY version. I got GOTY burned when Fallout 3 came around and I had to ...

I just ran the freshly installed demo and got an error containing the following: Value was either too large or too small for an Int32. This is on Windows 10. I suspect the full game might also crash upon startup.

I originally bought the regular version of Arkham Asylum and I noticed Steam now says I own the GOTY edition. However if I try to install and play it I get a Securom prompt asking for a serial key and there is no "View CD key" option if I right click the game in my Steam library . So basically I cannot play this game at all anymore....