Panel plugin not found: briangann-datatable-panel"

I installed the Datatable Panel plugin from https://grafana.com/grafana/plugins/briangann-datatable-panel/installation by downloading the zip file and unpacking it in the grafana plugins directory. I see the plugin installed, however, every time I try to add a panel, I receive the error, “Panel plugin not found: briangann-datatable-panel”. I’m running Grafana 6.2.5.

What can I do to successfully add the panel?