Enter a statistical key figure o r group

What causes this issue?

In cost center and order planning, you can either access planning with
a single statistical key figure or with a group of statistical key
figures. However, you cannot go in with both simultaneously.

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?

Delete either the statistical key figure or the group of statistical
key figures, or
Enter a value in one of the fields.

Error message extract from SAP system. Copyright SAP SE.