Hacking PSP ISO's Black Screen

[OldGnashburg]

When I try to launch a PSP disk that's on my FAT32 SD through Webman games. It will launch, but it will be a black screen. I can press the home menu but it will reset the PS3 if I try to leave. I am using a 256GB Lexar MicroSD. I remember seeing Aldostools saying on psx-place that PSP works from FAT32 SD. Is there something else wrong? Is booting from SD really slow or something?