Dreamcast IMG file help

I was able to attain for myself a marvel vs capcom 2 IMG file which is 725 mb's, so i am assuming this is the right one to download because the palce where i got it from wasid that chankast emulates it. now the problem is that i do not know how to get this thing working on my chankast. i used magiciso to turn the img into an iso. i used damon to mount the IMG file, and the ISO i made from magiciso. but whichever one i mount (IMG or ISO), Chankast keeps recognizing it as an audio file. i am wondering if there is something i am doing wrong. or is there something that could be wrong with my files, lets say oh i dont know, something that starts with a B and ends with IO.