Nintendo release new firmware DSi V1.4.4, and this updating blocked some flashcards, before update your DSi console, please sure if your R4i card or other flashcard work on the newest firmware. We have tested some flashcards, and get this:

NOT WORKING:

R4I GOLD PLUS (r4ids.com)
R4I SDHC 3DS (r4i-sdhc.com)
R4I SDHC V1.4.3 (r4i-sdhc.com)
R4ITT black/purple (r4itt.net)
R4I-GOLD 3DS (r4i-gold.com)
R4ISDHC V2.20t (r4sdhc.com)
TTi (ndstt.net)
Acekard 2i (acekard.com)
DSONEi mini (supercard.sc)

WORKING:

R4I GOLD 3DS (r4ids.cn)
EZ Flash Vi
Supercard DSTWO

If your R4i card can not work on new firmware, don't worry about it, I think the factory will release new kernel or path soon, keep waiting for a few days.