so your wii is hopefully a PAL system?
What kind of card are you using? this can have a major impact if it is working or not. Highest success rate so far is on a 2GB SD card (brand: Sandisk) (no mini/micro cards with adapter or 2Gb+ SDHC cards, some work, most don't) .
Try a different card, reformat to FAT32 using the supplied formatter tool of the guide.