BO1 Custom Zombies doesn't work with Radmin?

[Punsie McKale]

I've gotten WaW and BO2 to work with Radmin (just joining through Custom Games and connecting via Radmin IP). BO2 "Official" method of inviting friends doesn't work, but it's fine for me because Radmin works.

BO1 is another story. It doesn't allow hosting through Solo Play (no sessions are available error). Through Custom Games, I can join solo by force starting the game with xpartygo, but then connecting through Radmin loops forever (stuck on connecting screen). Using "official" method of inviting friends into the lobby results in "unable to join session" error.

Is anyone else having trouble hosting BO1 custom zombies?