Persistence, Sitemap Charts blank?

[openschwall (Peter Mueller)]

maybe this is the issue?

[SOLVED] Charts unique name problems

Dear Community! I have started using charts, but now I have some problems with it. I have one chart which works fine (my phone’s battery level on it). However if I want to add another chart which is a Group with more battery levels in this group I get this error: 2018-03-31 19:56:06.669 [WARN ] [thome.ui.internal.chart.ChartServlet] - Illegal argument in chart: Series name >Battery Level< has already been used. Use unique names for each series!!! Any ideas? Thanks