Problem with campaign editor units

[PrisonLove]

I created a bunch of custom units and heroes in the campaign editor (to use in the campaign, obviously), but when I go to test my map in the world editor, it resets those units to their defaults.

Here is the specific instance:

I created a Mario hero based on Arthas, with custom abilities and all. Then when I go to test the map, it has the model of Arthas and the normal abilities even though I gave it a custom model and custom abilities.

Is this supposed to happen? If so, how do I correctly test the map?

P.S. In the world editor it has the correct model and everything.