You can find the CID using a copy of The Biggest Loser.
As for the console ID, try decrypting a DSiWare .bin file that you have copied to SD using Data Management and look in the footer for a 16-digit string. That is your console ID.
If you are using a SD card adapter, those can go bad. Even though your computer can see it, something about the fault prevents it some working on the DSi.