When Animal Crossing: Let's Go to the City was released, Australians discovered, to their
horror annoyance, that the DS Suitcase feature was unusable in their region. Since the Australian release of Wild World on the DS used the exact same code as the North American version, the Wii game identified it as coming from the wrong region.
Australians who would like to be able to transfer their DS characters and catalogs into Let's Go to the City are advised to contact Nintendo to exchange your disc for a new replacement, which will allow the DS Suitcase feature to work with Australian copies of Wild World. Unfortunately, of course, if you want to use your DS character, that means starting over in Let's Go to the City.