NDS having problem reading game cart

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

Maybe you just screwed it up. Does it still have warranty?

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.

how do i check thier alignment?

Like I said, check if they're the size shape and angle as your newer carts. If so, something is wrong with your DS.

well i'll try to take some picture when i have time, you can check it for me?

Sure. Make sure it's completely straight with the cartridges though.