Grafana: Plugins installation

Hi!

Im trying to add new plugins to my grafana, but i dont have internet connection in that server.

I downloaded piechart-panel.zip in my pc and moved to /var/lib/grafana/plugins there and decompressed it

When I restart grafana service, i obtain this:

t=2017-11-29T15:46:31+0100 lvl=warn msg=“Could not scan dir “/var/lib/grafana/plugins” error: open /var/lib/gra…on denied”

In grafana, im not able to see my new plugin to use in a dashboards, I only have by default panels.

My permissions are correct -> grafana:grafana
my grafana version is 4.5.2

So, I dont know what im missing.

Any suggestion is welcomed.

Thanks!