Select at least one entry before choosing this function.

What causes this issue?

You have called a function, which can be performed for several entries
in the list screen. However, you have not selected any entries for the
function.

System Response

To prevent data loss, the system will not perform the function.

How to fix this error?

Please mark the entries, for which you want to perform the function and
call the function again.

Error message extract from SAP system. Copyright SAP SE.