What is a missing relation?
A Missing Relations warning indicates that a data point in your chart is not part of the current location. For example, when you have selected an EC measurement (of a water system) in a chart within a compartment.
Resolving missing relations
To solve this missing relation, go to Setup mode and click Assign (or the red question mark).
From there, you can edit the relation by selecting the desired installation part from the dropdown. Or select Not applicable to stop the data point from appearing in the chart at this location and suppress the Missing relations warning. After assigning a relation, a blue link icon will appear next to the item. You can click on it to edit the relation.
Operator will remember that relation for all future charts, so you only need to set it once.
You can only select 1 object for this relation. The color and axis will be the same on all locations of this chart, even if the relation is different.
If you need to show multiple objects of the same variable type, check out Compare different locations in a single chart on how to do that.