DJ autoboot mysterious help !!!

when I download a game selfboot (I tested toy racer) and I burn mod1 blosk 2352 offset0 cdda, all it's ok the game run on my dreamcast. But when I do an image with DJ (with all selfboot Daytona, snk oy toy racer etc) at the final of burning the game doen't run on my dream !! So why?? help !!!!

I have dj3