As we know that 3DS firmware has been updated to new V2.2.0-4 and it is said the new update can block flashcards. DOnt update until you make sure your flashcard can still work ont the new firmware. so far, ak2i official site has released the news that ak2i users dont update until they release the patch to support it. Another, R4i gold official site has released the news that their card can work on 3DS V2.2.0-4, they also released a video to confirm it.
From Acekard 2i
Do Not Update 3DS to 2.2
Please do not update your 3DS to 2.2 if your console prompt you to update. We'll release update file for AK2i ASAP. Please be patient. Thanks.
Good news! R4i Gold 3DS can support Nintendo 3DS ver 2.2.0-4(J,E,U) successfully! (2011-11-05)