It sounds like you are doing everything right. Use RNM 4.50 build a .gi and burn. You are using good media. Your ps2 laser might need a cleaning.

Chaos Legion
 

I have burned a successful copy of Chaos Legion using Verbatim DVD-R. Verbatim is the best media for burning PS2 games along with Ritek. Try not to use any cheap or dirty media, as some media just wont play. Also, make sure which program you are copying the disk with, Alcohol 120% is the best program out there, but Nero and Record Now Max work great too.

Alcohol 120%...i wouldnt say its the best program out there....i would say its one of the best out there :D

im just a big RNM fan...hehehe

i burned 3 copies of this game and i cant get it to work eather first 2 burned but had errors useing RNM so i burned with primo 1x it burned but left a dark burn error like the finlize part on the outter part of the disk and i put it in my apple it loads and says ps2 logo then just stays at a black screen and laser makes all kind nosies but will not load i watsed 3 dvds on it ive given up on that game