Out third party software knowledge is broad, but not necessarily deep. So beyond the basics, we are not particularly expert in configuring each piece of software for individual usage scenarios.

So I suggest that you consult the Observium docs. If that doesn't seem to match your experience, please ensure that you have the latest upstream version installed (and if not please update that first - FYI TurnKey is based on Debian). Then retry.

If you get stuck, please consider posting on the Observium mailing list. Please ensure that you have ensured that Observium is up to date first and that you follow their rules.

Also, once you've worked it out, please do not hesitate to post back so the next person in your shoes doesn't need to do so much leg work! :)