player market value, why didnt increased Options

[eyadoo]

Hi there,
i wonder why the players market values didnt increase after upgrading his skills.
for ex:
i have player 25 yrs old plays as CM, his value was 22.842
skills: Dribbling 11 ,Endurance 16 ,Passing 17
when i incresead his Dribbling to 12 the player value didnt raised. why ??