Manual entries are not possible (area defined to adopt identical values)

What causes this issue?

You specified a depreciation area in which the acquisition value is to
be reduced by investment support.
This depreciation area &V1& is defined so that it automatically adopts
values from area &V2&. You cannot, therefore, enter values manually in
this area.

System Response

The system deletes your entry.

How to fix this error?

If you enter area &V2&, the system automatically reduces the
acquisition values in this area and in area &V1&.

Error message extract from SAP system. Copyright SAP SE.