Diagnosis
While checking the screen, the system discovered that the screenadministration information (entry in table D021S) is either seriouslydamaged or missing altogether.

System Response
Even if the entry in table D021S still exists, the screen has beendestroyed from the point of view of the system.
The system requires at least the program name and screen number to beable to identify a screen. One of these parameters is missing or cannotbe interpreted, so the system cannot allow you to edit the screen.
If the message appears when you try to display versions of the screen,the screen was already deleted when you called this version.
If the message appears when you compare two versions, the screen wasalready deleted in at lease one of the two versions when you calledthem.

Procedure
Consult your system administrator.