Impossible to retrieve "Created By" column ($Author) in JSON View formatting

Hi Everyone,

I tried to format a view for my sharepoint list using JSON . All look work well, except the "Created By" column retrieve.

By retrieving "$Author" variable in my JSON, in order to display 'Created By' metadata, I have an error in my sharepoint list. I can not display the displayname of the person who created item using JSON formating. 

Could anyone can help me how to fix this kind of bug ?

Thanks in advance,

Charles