It should be "JS injector" instead of "JS Injector" (no capital "i" in "injector"). Please see here why: #1103208: Projects' names should be checked in .info files for correct capitalization.

http://drupal.org/node/1205630

Thanks to javiernovoac

#747670 - Serve js files over public method if possible.

#600834 - add implementation of hook_file_download to ensure js file is accessible over a private file system