Running PCE ROMS In SuperCard MiniSD

Hi all, they said that the SuperCard have built-in emulators right? And one of them is the PCE emulator (Turbo Grafx). I got some ROMS for it, and most people say that I should just directly copy it to the MiniSD. But when I try to play it, all I get is a black screen. When I press the L+R, the PCE emu menu appears... what might I have done wrong?Thanks in advance!