Categories in Table Layout

Hello,

I want to show a Column "Category" in the Table Layout. I've seen this is alreay in the code (common/document_table.php), but where is the option in the configuration or the menu-setting to activate it?

I've got this column when adding &show_category=1 to the url. But then only the tablehead is filled. This column is empty in all documents



Have I done anything wrong?

Thank you,

Michael