When I plug in the Camera Connector on my IPad 3, I get an error message "This accessory not supported by IPad". It is a genuine Apple Camera attachment purchased from Apple Store. The SD card reader works great, so no problem with it.
Make sure the 30 pin dock connector on the USB adaptor isn't damaged or dirty, if that isn't the case, plug the camera in, and then the adaptor. If that doesn't seem to work the adaptor may be defective.