Select sub-tree first

What causes this issue?

The <LS>Reassign</> function reassigns a selected sub-tree to the
(target) node where the cursor is located.
You attempted to execute this function, but did not select a subtree.

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?

Select a node in order to transfer the associated subtree. Then, place
the cursor on the target node and proceed with the reassignment.

Error message extract from SAP system. Copyright SAP SE.