It sounds like you updated your iEDGE card to the iEDGE 1.4.3
firmware that Nintendo released for the DSi and DSi XL a while back.
It's quite probable that your iEDGE isn't updated, and then you updated
your console which will cause the iEDGE to not work.
Take a look at this site for a bit more information:
iEDGE Not Working on Firmware 1.4.3 DSi Version
iEDGE Production Shortage in September 2011
I'd recommend getting a card with a team behind it that has a little more support. Names that come to mind include the Supercard DSTWO
, Acekard 2i
and Cyclo DS iEvolution
, all of which are pretty top quality cards with frequent-ish firmware updates.
I personally shop at DSCardWorld.com but if you live outside of the U.S.
then NDS-Gear.com is likely to be your best bet for an authorised
retailer where you don't run the risk of picking up a knock-off fake
Hope I've helped, and please upvote my answer if I have! :-)