Crowdsec init: while loading acquisition config: no datasource enabled

Hello guys! I’m currently trying to setup my first data source:
acquis.d/journalctl.yaml:

source: journalctl
journalctl_filter:
  - "-k"
labels:
  type: syslog

however, I’m getting the following error message:

crowdsec init: while loading acquisition config: no datasource enabled

may I ask what I’m doing wrong?

Ok, maybe this gives a bit more context: I’m on NixOS and it looks like that it didn’t copy my journalctl.yaml into the acquis.d directory…