Original post by: Jake McCready ,
before replacing the card, try and push on the back of the DSi approx. where the wifi card is. If that doesn't work. open the DSi case then disconnect and re-seat the wifi card. That ended up working for me. I guess the connector was a little loose. The connector doesn't really have any kind of grab, it is just seated so the regular jostling that a portable game system goes through will eventually unseat it.