Sometimes I find using eBoot makes more games run. You can try converting a .bin or other image format to an eboot using Impaler. Just google "Impaler PSX eBoot Creator" and its the first link. Also be aware that not all games will actually run in the emulator, I have run into a handful that sat at the black screen and wouldn't load. Basically everything looked like it would start and then it just sat at a black screen.
You can also try clearing the settings and then restarting the app and setting the BIOS again. Make sure you are using the scph1001.bin bios also as I don't think it will run using any foreign or alternative bios. As a final note although I'm not sure it will do much you can also delete the .psx4droid folder on your SD card.
What phone are you trying to run it on also?