Photo accessorie

How did the photos get onto the card, direct from the camera or have you copied them onto it form your computer ? If you've copied then you need to create a DCIM directory off the root of the card, with the photos underneath it, and the photo filenames need to be exactly 8 characters long (no spaces) plus the file extension i.e. in a similar format as if a camera had created/written them.

If it's come straight from the camera then is the kit firmly inserted into the iPad's dock ?

Try a reset and see if it's recognised after the iPad has restarted : press and hold both the sleep and home buttons for about 10 to 15 seconds (ignore the red slider), after which the Apple logo should appear - you won't lose any content, it's the iPad equivalent of a reboot.