like I said, +di requires at least ONE discEx'd game on USB, or it won't boot.
so, you need it in the proper format, in proper folder's name.
Di (disc interface) is only useful to play disc based games which are not working with USBLoaders (tintin for example).
if you want to play a non problematic game, don't bother to use neek, or try to use di just for the fun to have all that exists, just use an usbloader on sysNAND.