Sounds like you haven't copied the correct files to your FLASH0 - i suggest you re-read the tutorial and make sure you copy the correct files. (did you copy the 'original' ones instead of the 'USB' ones?)
Of course you also need to make sure you have all 3 plugins turned on too - so check that as well.
usbhostfs.prx [VSH]
buzzusbvsh.prx [VSH]
usbhostfs.prx [GAME]
Must all be enabled.