add_space_permissions is not working

[govind45]

Trying to run api to add space permissions but it's always returning 404, tried with multiple options but no luck. Any help is appreciated. url: <my_conf_site_url>/rest/api/space/CTS/permission

body:

{ "subject": { "type": "group", "identifier": "pco" }, "operation": { "key": "delete", "target": "space" }, "_links": {} }

Output:

404 null for uri: /rest/api/space/CTS/permission