You said you were SURE the burn is good......???
How do you KNOW that if it won't PLAY???
You used Primo...Did you follow the tutorial at the top of the PS2 forum?
Primo Tutorial!!!!
What type of media are you burning on?
Have you tried any of the boot procedures in the "Sticky" Post at the top of the PS2 forum?
Boot Procedures!!!!
AND YES..... Get another mod chip...