Items cannot be added to inbound delivery: &1

What causes this issue?

Items of an expected goods receipt can only be added to an existing
inbound delivery if certain data is identical in both documents. This
data can be, for example, warehouse number, receiving office, or the
party entitled to dispose.
For expected goods receipt &v4&, the value of field &v1& &v2& in the
selected inbound delivery is &v3&.

System Response

The selected items cannot be added to the selected inbound delivery.

How to fix this error?

Check your entries. Select a different existing inbound delivery, other
items to be copied, or, if necessary, create a new inbound delivery.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.