can't load more than one kit in kit rack

Brand new to Groove Agent, just learning some basics through tutorials, the forum, etc. For some reason the kit rack only lets me load a kit in the first slot. The other slots are just black, unlike every tutorial and picture I see where blank slots have greyed out kits images. When I try to drag a 2nd kit to another slot I just get a “do not enter” circle-with-a-line symbol. What’s going on here?

Are you using SE or the full version? SE only allows 1 kit to be loaded.
If you are on SE and want more kits, just load more instances of GA.