Check if it has a switch on the side for USB/ card reader. Should be a small black one. Try a USB keyboard to test if it works. Perhaps try removing your sd card from camera and plug that into the card reader slot, the pictures should load about 5-10 secs later. It may not be able to read the images via USB on your camera as it doesn't with one of mine. Also if your using an sd card, the only way the iPad can read them is if there all in a folder on the card named DCIM you can't have us folders neither.
Hope this helps, if not post a picture of the one your using someone may have the same kit. Mine is a iPad 2 on 5.1.1 but I still have the intermittent error messages occasionally.