This may sound utterly retarded, I know, and I'm willing to receive any criticism. Sanogo starts the game injured, and I was trying to sign him but, since he was injured, he was failing his medical. I fired a new game without adding any staff, didn't hire the physio and I could sign him alright. Just in case anyone was having a similar issue 
Probably works by just firing your physio, too.
Probably works by just firing your physio, too.