Did you try to use the acekard right out of the box? if so, you will need to reformat the mini-sd card and go to the acekard website and download the latest firmwire and updates.

For the people who are getting an "Error, hold the power button....", it means that your Dsi has the latest update firmwire, so you will need to update the Acekard firmwire that just came out. To do so, you will need a DS Lite and run the update (Also on the Acekard website).

Hope this helps.