If after your add-on was uploaded to the ReadyNAS and verified you receive an error message saying "Invalid checksum detected in the file. Update aborted" then in most cases nothing is wrong with the add-on file.
Instead you most likely downloaded an add-on for the wrong CPU architecture of ReadyNAS systems.
To determine the CPU of your ReadyNAS check the "Intel or Sparc" page on our web site.
To correct the problem all you have to do is to download the correct version of the add-on and try again. There are two areas on every add-on page where you can check that you're in the right section:
If that still doesn't work please contact us using an email to email@example.com.