My only suggestion is to try again - you may have done something wrong.
The devices can be a little picky for one of several reasons:
Your SD card is > 4gb (for update purposes the reader prefers smaller cards)
The folders/files aren't in the correct place on the SD card.
Something happened when copying the files onto the SD card.
Try deleting the files from the SD card, re-copying (and waiting for a few minutes after it's done the writing) and doing the update again.