why some isos on the SSF work and others dont?

Why do some games mount and load on the SSF like Soukyugurentai, Shienryu, Layer Section 2,Christmas Nights,Guardian Heroes and Clockwork Knight, but games like Bulk Slash, Mass Destruction, Assault Suit Leynos 2 and Metal Slug do not?
I use virtualclone as the mounting device. Is Daemon that much better? Or is my problem related to something else?

Where did you download the ISO?
As there have been a report that some of SS ISO have error in it, and need to be repaired.Try to repair the ISO,
using the CDMage.and the load it again, see if it works. :)