Grafana service does not start after reboot

Installation:

wget https://dl.grafana.com/oss/release/grafana_6.1.6_armhf.deb
sudo dpkg -i grafana_6.1.6_armhf.deb

(https grafana com/grafana/download?platform=arm)

Systemctl: --> if startet grafana manuel. After reboot, grafana does not start automaticly

sudo systemctl status grafana-server

● grafana-server.service - Grafana instance
Loaded: loaded (/usr/lib/systemd/system/grafana-server.service; generated; vendor pr
Active: active (running) since Sun 2019-04-28 16:41:49 UTC; 1 day 2h ago
Docs: http docs grafana org
Main PID: 747 (grafana-server)
CGroup: /system.slice/grafana-server.service
└─747 /usr/sbin/grafana-server --config=/etc/grafana/grafana.ini --pidfile=/

Apr 29 19:02:24 raspberrypi grafana-server[747]: t=2019-04-29T19:02:24+0000 lvl=eror ms
Apr 29 19:02:24 raspberrypi grafana-server[747]: t=2019-04-29T19:02:24+0000 lvl=eror ms
Apr 29 19:02:26 raspberrypi grafana-server[747]: t=2019-04-29T19:02:26+0000 lvl=eror ms
Apr 29 19:02:26 raspberrypi grafana-server[747]: t=2019-04-29T19:02:26+0000 lvl=eror ms
Apr 29 19:02:26 raspberrypi grafana-server[747]: t=2019-04-29T19:02:26+0000 lvl=eror ms
Apr 29 19:02:26 raspberrypi grafana-server[747]: t=2019-04-29T19:02:26+0000 lvl=eror ms
Apr 29 19:02:32 raspberrypi grafana-server[747]: t=2019-04-29T19:02:32+0000 lvl=eror ms
Apr 29 19:02:32 raspberrypi grafana-server[747]: t=2019-04-29T19:02:32+0000 lvl=eror ms
Apr 29 19:02:32 raspberrypi grafana-server[747]: t=2019-04-29T19:02:32+0000 lvl=eror ms
Apr 29 19:02:32 raspberrypi grafana-server[747]: t=2019-04-29T19:02:32+0000 lvl=eror ms

Thanks for your support.