For the greatest security and browser validation, all SSL certificate installations should include an intermediate bundle. Comodo offers all of its intermediate bundles on their website:
When installing your certificate, make sure you visit the link above and download the correct intermediate bundle for your certificate. Then paste it into the SSL Manager within cPanel, at the time you activate your SSL certificate.
Once the certificate is installed, you can verify it is validating correctly in your browser by viewing the certificate details (normally accessed by clicking on the certificate icon in the browser’s address bar. Click for more details, and you should see the intermediate certificate chain, like this: