Eh, did you get the CF card from the same shop you got your camera from? Can always go back and complain and exchange for another brand - must be lousy sales person... The read/write speed does matter, if the card's speed is too slow it'll not work with the camera, that's why I always get the first card (for the camera) from the shop that sells you the camera - same day. (That's my insurance.)
Where is Twinmos made in?
Hope you're able to get an exchange (maybe top-up a little) - go for the American brands (1st choice), Japanese brands (2nd choice, costlier), no third choice - normally not reliable or Read/Write is too slow...
I uses LEXAR (1GB), because ScanDisk Ultra II was a little costlier.
My choice was based on Read/Write speed.
Good luck on your exchange - put your foot down but be friendly, it helps to get a faster exchange. :sweat: