Anyone know about boot disks and burned games?

Hi! i recently bout 5 burned games off ebay from a guy in washington, (i live massahcusettes) but anyway, only one is self bootable, so i had a friend get me a utopia boot disk, and it ####ts up fine in the dreamcast and everything, but when it asks to insert the cd, i take the boot disk out and put in burned game, but it still makes the wierd loading sound as if i never had the boot disk in it. am i doing osmething wrong? is there a special disk i need? PLEASE help me!