My player's value is not increase !!

[Narf]

No it's not a bug...your players value doesn't go up as you add skill points...a young player might increase in value over a couple of seasons yet an older one won't...

Not true.

The value depends on the player's form...

And again IMO not true.

Some players' value just increases "faster" than other's, you might need to just add more skill points. I've seen values increasing per skill point for some (young AND expensive for that level) and then for other players - per quality point, where depending on the player it might be either 1q point (5 skill points) or 1 overall quality point (15 skill points).