Help, the games won't boot...

[gamezource]

Hi, I have burned some self-booting games like Capcom vs SNK and The House of the Dead 2 (they were CDI files and I converted them to NEro .nrg files cuz my discjuggler won't work...)

But they will not boot in my DC, why? Is it because that I converted them to Nero files? Someone please help, I am very stressed about this problem...
And can someone teach me how to use a boot disc? Do I need to do the swap trick with the Utopia boot disc? Please help me out, thanks a lot!!!