New contracts

I am managing Southampton, 6 months left on a fair few first team players contracts and I am 2k under my wage budget. Now I understand that if I was trying to sign a new player I would have limited amount of wages as I am close to the max budget. However, why can't I offer a player the same wages as he is on currently. This will in no way affect the wage budget - it will stay the same. I can't even offer 1 or 2k under. My finances are secure (not in the red).

This has been the same for the last couple of versions of the game. Any advice?