In ACE Agent, support function Unifinder Ctrl Alt A opens and closes the Activities tab, to the right of the search result.
Select relevant person(s) in the search result.
In the Activities tab, click on the plus button + or press Ctrl Alt H to open the Set activity window.
             
        
In the Set activity window,
If an activity cannot be set you will get information  about the reason.
 about the reason.
To change or remove an activity: