well my NDS is having problem reading my Pokemon Pearl and my R4DS, it offen cant detect it, so anyway to solve this? Note: it can read new game cart without a problem
Is there dust on the carts or in the slot? Dust is usually the reason why games cannot be read. That, or something is very wrong internally
Nothing wrong with your carts if both of them aren't working, most likely the reader of the NDS can't detect it. If you use Pokemon Pearl and your R4 regularly, maybe the placement of the cart isn't aligned correctly. Best to see if you can get it fixed by Nintendo. Check if Pearl and your R4 are the same alignment as your newer game carts.
Like I said, check if they're the size shape and angle as your newer carts. If so, something is wrong with your DS.