Hello again,

looking at your current robots.txt file i don't see any directive blocking links for images from your CDN.
Eventually try to remove the following:

User-agent: Mediapartners-Google
Disallow:

Also take care that when you edit the robots.txt it's not immediate effect in Google Webmasters Tools, you have to resubmit it and it may take up to 2-3 days to be refresh and be effective. So it could still be blocked on a previous version of the robots.txt blocking image.

After you wait some days you can even resubmit the sitemap using a different link to be sure that it will be refreshed.

Thank you

John