Problem with playing PS2 game

Hello.
I have ps3 with latest rebug CFW. I tried to play ps2 game, but the ps3 freeze.
I put the ISO in PS2ISO folder and loaded it with webman mod (tried multiman also), but the ps3 freeze after loading the game.
I don't have other ps2 game to try.
Do i have to edit the ISO somehow or tweak it to make it work?