Well, yeah. The card reader can use an SD card. The other possibility is that the card reader can only handle SD cards and not SDHC like the card is. I'd try a 2gb or smaller card in the reader and see if it can read it, then try a regular SD card of 4gb or greater and see if it reads. That'll tell you if the reader supports SDHC. If it can't read the larger SDHC card, then you need to get a new reader.