Function can only be called for items

What causes this issue?

No item has been selected to which the function called should be
applied.

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?

The cursor must be placed on an item in the list before the function
can be called.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.