The selected directory does not belong to a Macintosh-Accessible volume. The Macintosh view of directory permissions is only available for directories that are part of a Macintosh-Accessible volume.
If you'd like to make the directory part of a Macintosh-accessible volume, select Create Volume from the MacFile menu in File Manager. In order to tell which volumes are Macintosh-accessible, use the MacFile menu in either Server Manager or File Manager. From the MacFile menu in Server Manager, select Volumes. From the MacFile menu in File Manager, select View/Modify Volumes.