Can't run roms on PSP

I downloaded the latest stable build for my PSP, but I can’t run any roms on any core. Retroarch itself boots fine and loads cores properly, but as soon as I try to run a rom for any of the cores, I get a black screen. When I try to leave the emulator via the home button, my PSP turns off by itself.

I’m running CFW 6.60 PRO C2.

are they Zipped? There were problems with roms being zipped on other platforms.

Nope, everything is unzipped.

thanks . it worked