Separate versions of the plugin "Quiz Reports: CBM Grade Summary" are required for Moodle 2.5, 2.6, or 2.7/2.8. So far as I can tell they are all set up correctly on the plugins site:
If you opt to download the correct version of the plugin you get it fine and can install it - no problem. But if instead you adopt the alternative procedure of clicking "Install Now" for the correct version, you don't get this version at all, but instead always the version for 2.5 (even though that is explicitly not valid for your more recent Moodle, and even if that version has been ostensibly hidden). I can't figure out what is wrong. Can anyone help?