Linear data cannot be maintained for characteristic value &1 &2 &3

What causes this issue?

You want to specify linear data for the characteristic value &V1& &V2&
&V3&. However, this is not possible for one of the following reasons:
The characteristic or characteristic value is not defined in the
classification of the technical object.
The characteristic is not specified as a linear characteristic.

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?

Check the classification data for the corresponding technical object.
Make sure that you have set up an organizational area relevant for
linear asset management and that you have assigned this organizational
area to the class and to the relevant linear characteristics.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.