Cost element already exists from & to &

What causes this issue?

The cost element is already fully or partly defined for the interval
&V1& - &V2&. You can only add a cost element if it does not exist at
all in the entire interval.

How to fix this error?

Use <DS:TRAN.KA03>display function</> to check in which interval the
cost element is already defined. You can create the cost element in
periods for which it is not yet defined.

Error message extract from SAP system. Copyright SAP SE.