SAP Message 5A479 - Activate preview mode in the detail screen

Diagnosis
There are two ways to display data in the detail screen: preview mode,which displays the current status in the preview period and time-dependent mode, with which you can follow the chronological course ofthe data.
In the preview mode, the display period of the detail screen issynchronized with the preview period of the overview screen.
Preview mode must be activated for the action you have chosen.

System Response
The action has not been performed.

Procedure
Switch to preview mode before you try the action again.