View field &-& (domains of the data elements not equal)

What causes this issue?

A data element which has a different domain than the base field
was allocated to a view field.

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?

Normally view fields refer to the data elements of the base fields.
You can ensure this for the view definition in the
ABAP/4 Dictionary by switching off the modification flag for the view
fields.
If another data element is to be allocated nevertheless, make sure
that at least the domain of the base field agrees
with the domain of the data element.

Error message extract from SAP system. Copyright SAP SE.