Hi Josh,
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 VersioniEDGE Production Shortage in September 2011I'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 card.
Hope I've helped, and please upvote my answer if I have! :-)