Hey, that's the same problem I was having. I think this should be put up in sticky FAQ. This is my theory, I could be wrong:
Indication: Some newer games (numbers 500 and up) doesn't want to work, all you get is blank screen, and if you turn on emulation speed to "Unlimited Mhz disaster, 10%" the percentage in title bar goes way up (this means that emulator is doing nothing, it's stuck).
Solution: You'll need the firmware.bin. After you copy it to no$gba folder (the same place where bioses reside), select "Reset/Startup Entrypoint" in Emulation Setup, save setup. Restart game, or even better - close and start no$gba again, now after selecting nds file, it will go to nds menu.
Now, the most asked question (which will be asked again and again and again): Where to get firmware.bin? Answer: the same place you got bioses (if you got them legally
). No need to hide, that after some time (I estimate a few months or so, I could be wrong, of course), after the NDS emulation really cathes on, you will be able to get the firmware as easy as the one for PSP. For now - please stop asking about it, it won't do any good, especially as the games are still far from playable (saves are not working, emulation speed is slow, no sound etc.). Use emulator to check out the cool homebrew stuff, for which no illegal files are needed.
