Try this:
Turn on iPad
Plug camera USB/SD card reader into port
Insert SD card
Open Photo App
Within 3 seconds, the photos should appear.
The USB portion will never work with anything, other than when it is connected to something else that supplies the power. i.e. Connecting a powered camera to it. In which case follow the same steps above, substituting the cameras USB for the SD card.
If this does not work, you may have a faulty reader.