Generally, you would add custom POIs to such a Kenwood/Garmin system using POI Loader like this:
  • Add the files to a USB storage device such as a thumb drive (X:\Garmin\*.gpi)
  • Plug the USB device into the DNX's USB port
  • On the screen a prompt should appear, select "Yes" then "Custom POIs" then
    "Install"

If that's what you followed, are the POIs you installed searchable?