chmod not letting me change permissions

I've used smartFTP in the past to change permissions of files, but now for some reason there is one file that it is not letting me change the permissions of. When I go to change permissions, it say's that the permission is " 0 ", I want it to be 444, but when I try it say's " command not understood ". I called my hosting company to see if they don't allow users to change permissions of files, but that wasn't the issue. Does anybody have any Idea of how I can fix this?