Help! When I plug my Canon Digital Rebel XTi into my MacBook, nothing comes up to let me transfer my photos from my CF card to my computer. I also have an Olympus E-500, but I have no problems transferring photos from my Olympus to my MacBook. When I put the CF card in my Olympus, everything works just fine, but when I try to transfer from my XTi, nothing happens when the camera is plugged into the computer. Can someone please tell me what I should do to be able to transfer directly from my XTi? Thanks!