Use Modio, works fine for me.Sorry about this, but I will just tell you what I did and let the whole community laugh at me. :P
1. I downloaded this file
2. I injected savegame.foo to Horizon
3. I made the profile and console ID on the gamesave the same as my accounts profile and console ID.
4. I saved it.
5. I plugged my usb back into the xbox where it said under games and apps 'Call of Duty: Black Ops II World State
6. I started playing black ops 2 on my account
7. I chose the usb as my save storage
And when I chose campaign the only option is new game. Have I done something wrong? Should I have completed the first level of the campaign before I started the transfer. Please help someone, I would really appreciate it.