OpenVPN at system start is not working

I'm trying to automatically connect to my openvpn server during system start, right after the network service come online.

I'm using the method described in /storage/.config/system.d/openvpn.service.sample

But at system start the following messages are found in the log:

XXXX RasPlex systemd[1]: [[0;1;39m[/storage/.config/system.d/openvpn.service:X] Unknown lvalue 'Requires' in section 'Service'[[0m
XXXX RasPlex systemd[1]: [[0;1;39m[/storage/.config/system.d/openvpn.service:X] Unknown lvalue 'After' in section 'Service'[[0m

The value in Requires and Afer are:

Requires=network-online.service
After=network-online.service

But when I start the openvpn service manually it starts normally and works.
systemctl start openvpn.service

Why is the openvpn service not automatically starting?