Plant &1 is not assigned to distribution chain &2 &3

What causes this issue?

No entry was found for plant &V1& and distribution chain &V2& &V3&. It
is possible that the plant is not participating in the promotion, or
does not belong to the distribution chain you entered.

System Response

The system cannot activate the prices for this combination of
distribution chain and reference plant.

How to fix this error?

Select a different distribution chain and/or reference plant. Ensure
that the reference plant is participating in the promotion, and belongs
to the distribution chain.

Error message extract from SAP system. Copyright SAP SE.