Problems with loading plugins

Carla doesn't recognized at all as an lv2 plugin. When loaded as a vst plugin, its window is empty (loaded within qtractor that is). Same with the Calf lv2 plugins, their UI is blank, and unresponsive. Patching the qtractor with Carla (on its own app, not as a plugin) for midi (master of qtractor to midi-in of carla), causes carla to crash. Overall, I was trying to find ways to use these Calf plugins with qtractor, but neither alone, or via Carla makes them work. In one case they fail on their own, and on the other one, Carla fails. I need to use plugins to make qtractor useful...