Selection of &2 required for calculation of key figure &1

What causes this issue?

In automatic planning you have chosen to calculate a basic key figure.
This is determined by a formula and is dependent on other basic key
figures. All basic key figures used in this formula must have
non-time-based aggregation SUM.
Select the basic key figures on which the basic key figure to be
determined is dependent.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Error message extract from SAP system. Copyright SAP SE.