Functional location label must not be initial in the first block

What causes this issue?

You have entered a functional location label that has a first hierarchy
block consisting of blanks. This is not allowed.

System Response

INCLUDE 'KEINE-VERARBEITUNG' OBJECT DOKU ID TX LANGUAGE EN

How to fix this error?

Complete the first hierarchy block. Even if you are not immediately
going to enter a master record for a functional location at the first
level of the hierarchy, you still have to fill the first block with a
character for all the functional locations below. Only in this way can
you extend the functional location upwards (in other words to the first
level of the hierarchy should this be necessary at a later date),
without the generic structure of the functional location label being
lost.

Error message extract from SAP system. Copyright SAP SE.