Select a & or place the cursor on a &

What causes this issue?

Before you can execute a function, you must first select one or more
objects or place the cursor on one object.

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?

First select one or more objects or place the cursor on an object. Then
execute the function.
If objects are selected and you have placed the cursor on an object,
the function is only executed for the object at the cursor. The
selected objects are then deselected.
If you want to execute the function for several objects that you
select, you have to execute the function via the menu. The cursor must
not be positioned on any object.

Error message extract from SAP system. Copyright SAP SE.