NDS Lite - black screen now?

I have a Nintendo DS Lite. I download my games and everything works fine. However, once I actually get the games onto my NDS and select the game, it doesn't load. Instead, it just stays as a blank white screen and I can't play. I have tried it with many games such as Mario Kart and Grand Theft Auto. There's nothing wrong with the games because it works completely fine for other people.
I have looked up things like updating the firmware.I tried to format my sd card, but now all I have is a black screen when I turn on my DS. It's definitely on, the light is on, but I just get a black screen. I am using a R4 card.
Any ideas? Thanks so much =]PS: Pardon me, I'm a newcomer, and I looked at the Common Problems thread, but I don't see my issue on it. Thanks a lot for the help!~ xwithaflourishx

Your issue is covered in the Common Issues thread. It's a compatibility issue with the ROM and what ever flashcart you are using. You don't mention what card you are using, R4, R4 III, R4 Upgrade, R4 Deluxe, M3, N5, Acekard, etc.The GTA problem is more specific, here is a thread on that https://www.romulation.org/forum/index.php?topic=14970.0