Game difficulty won't change (DBZ BT3)

[Creep]

Hello. I've been willing to emulate dragon ball z budokai tecaichi 3. It works quite well, but i can't get the difficulty to change. I set it to easy and in game it shows that it is on easy, but i still can't even beat the first oppenent in story mode. I've won tournaments in the game with difficulty of hard, but i can't compleate the first level in story with difficulty of easy.

Any ideas, weather it should be like that or maybe i'm doing something wrong?

EDIT: i guess, it's meant to be that way. Now i tried out medium and now the enemys seem invincible....