How to color log-entries from Loki&promtail

Hello there,

I’m using grafana 10.2.0 & loki&promtail.
IGrafana gets log-entries from a logfile via loki&promtail. That’s working fine.
But I want to display the lines colored according to content in the line-column.
I’ve tried it with value mappings (value or regex, neither works), and overwrites.
It seems, that the value mappings are not used in this constellation.

On another source with loki and pushed enries, it works fine.

Have some one a hint for me?

Thanks a lot

Kind regards