Added panels not showing

Hey all...

I was tinkering with some graphs and I noticed that the built-in Graphs is supposed to support Histograms, but I can't find it in the configs for it. I also added some other panels in and they show up in the Home page under Installed Panels, but I can't select them.

I added Carpet Plot, Bubble Chart and another Histogram panel...but can't choose them.

Am I just missing something in the documentation?

I'm using line graphs, but on some stuff like energy use I'd like a Histogram of bars showing the levels on some single-device data graphs.

Thanks
Ross