Barges and their carriers

[Grumbler]

I know that when you are loading a barge, you have to use a certain order. Normally, when loading a leg unit in a truck it doesn't matter which unit is active when you hit the 'L' key. With barges, it does. It has been so long since I last used a barge, I have forgotten which unit has to be active. I think it is the barge, but I won't argue when Narwin tells me I'm wrong.
Do you get a 'no room' error message? That would make sense, since a barge carrier has to be bigger then the barge to carry it.
I seem to remember something about barge carriers having multiple barges, which was deemed a bug and fixed. I didn't think of it as a bug, since a pontoon is sort of a barge and several can be carried on the same vehicle.
I was under the impression that barges came pre-loaded. Check and see if your barge carrier already has a barge on it. If so, that and the one barge per carrier bug fix would explain why you cannot load another barge.