The procedure to add gc100 is folowing:
1. Reset gc100 to factory defaults by power&lan off, short pins 2 and 7, while pins are shortened, plug the power, leds should blink, add network.
2. From orbiter or pluto-admin add gc100. On orbiter it should show that "software was installed" and "press quickreload to start using new device" (i'm not quite sure about messages, but this is the idea)
3. You should see gc100 under the CORE in pluto-admin.
1. See if package pluto-gc100 was installed (dpkg -l 'pluto-gc100'), and it must match the version of DCERouter.
2. See if the device is running (ps auxww | grep gc100)
3. See anything suspicios in log (tail -f /var/log/pluto/XXX_gc100.newlog)
I hope that this will help you.