Yup, power and space.
I never have issues with fixtures in the 3D Visualizer. Are you sure you're brining up those dimmer channels? It's a real easy mistake to make and overlook, especially if you're on sight and stressing over what you're doign. Not a good place to learn.
Could also be the profiles are wrong, but ADJ makes a pretty decent effort to ensure the profiles are done properly before distributing them. Jingles is making most of them, so it would seem, and he gets feedback from those he's making them for. My guess is that he knows profiles pretty good since I don't see complaints.
Double check your channels. One of my fixtures is a 7-channel fixture(64 LED PRO) and I have a blank channel between fixtures to maintain compatibilty with my DMX Operator(should I need it). I keep screwing up and grabbing that unused channel!