Key field & of object & is for navigation.

What causes this issue?

The field relationship type is specied as 'S', but the object field
&V1& is a key field which is used for navigation.

System Response

The view cluster was not activated.

How to fix this error?

Enter the field relationship type ' '. The specified
field dependency is then used in the navigation and for getting
dependent entries.

Error message extract from SAP system. Copyright SAP SE.